Combinatorial synthesis of novel materials

ABSTRACT

Methods and apparatus for the preparation and use of a substrate having an array of diverse materials in predefined regions thereon. A substrate having an array of diverse materials thereon is generally prepared by delivering components of materials to predefined regions on a substrate, and simultaneously reacting the components to form at least two materials. Materials which can be prepared using the methods and apparatus of the present invention include, for example, covalent network solids, ionic solids and molecular solids. More particularly, materials which can be prepared using the methods and apparatus of the present invention include, for example, inorganic materials, intermetallic materials, metal alloys, ceramic materials, organic materials, organometallic materials, non-biological organic polymers, composite materials (e.g., inorganic composites, organic composites, or combinations thereof), etc. Once prepared, these materials can be screened for useful properties including, for example, electrical, thermal, mechanical, morphological, optical, magnetic, chemical, or other properties. Thus, the present invention provides methods for the parallel synthesis and analysis of novel materials having useful properties.

STATEMENT OF GOVERNMENT INVENTION

[0001] This invention was made with Government support pursuant toContract No. DE-AC03-76SF00098 awarded by the Department of Energy. TheGovernment has certain rights in this invention.

FIELD OF THE INVENTION

[0002] The present invention generally relates to methods and apparatusfor the parallel deposition, synthesis and screening of an array ofdiverse materials at known locations on a single substrate surface. Theinvention may be applied, for example, to prepare covalent networksolids, ionic solids and molecular solids. More specifically, theinvention may be applied to prepare inorganic materials, intermetallicmaterials, metal alloys, ceramic materials, organic materials,organometallic materials, non-biological organic polymers, compositematerials (e.g., inorganic composites, organic composites, orcombinations thereof), etc. Once prepared, these materials can bescreened in parallel for useful properties including, for example,electrical, thermal, mechanical, morphological, optical, magnetic,chemical, and other properties.

BACKGROUND OF THE INVENTION

[0003] The discovery of new materials with novel chemical and physicalproperties often leads to the development of new and usefultechnologies. Over forty years ago, for example, the preparation ofsingle crystal semiconductors transformed the electronics industry.Currently, there is a tremendous amount of activity being carried out inthe areas of superconductivity, magnetic materials, phosphors, nonlinearoptics and high strength materials. Unfortunately, even though thechemistry of extended solids has been extensively explored, few generalprinciples have emerged that allow one to predict with certaintycomposition, structure and reaction pathways for the synthesis of suchsolid state compounds. Moreover, it is difficult to predict a priori thephysical properties a particular three dimensional structure willpossess. Consider, for example, the synthesis of the YBa₂Cu₃O⁷⁻⁸superconductor in 1987. Soon after the discovery of theLa_(2−x)Sr_(x)CuO₄ superconductor, which adopts the K₂NiF₄ structure(Bednorz, I. G. and K. A. Muller, Z. Phy. B 64:189 (1986), it wasobserved that the application of pressure increased the transitiontemperature (Chu, et al., Phys. Rev. Lett. 58:405 (1987)). As such, Chu,et al. attempted to synthesize a Y—Ba—Cu—O compound of the samestoichiometry in the hope that substitution of the smaller element,i.e., yttrium, for lanthanum would have the same effect. Although theyfound superconductivity above 93K, no phase with K₂NiF₄ structure wasobserved (Wu, er al., Phys. Rev. Lett. 58:908 (1987)). Even for therelatively simple intermetallic compounds, such as the binary compoundsof nickel and zirconium (Ni₅Zr, Ni₇Zr₂, Ni₃Zr, Ni₂Zr₈, Ni₁₀Zr₇, Ni₁₁Zr₉,NiZr and NiZr₂), it is not yet understood why only certainstoichiometries occur.

[0004] Clearly, the preparation of new materials with novel chemical andphysical properties is at best happenstance with our current level ofunderstanding. Consequently, the discovery of new materials dependslargely on the ability to synthesize and analyze new compounds. Givenapproximately 100 elements in the periodic table which can be used tomake compositions consisting of three, four, five, six or more elements,the universe of possible new compounds remains largely unexplored. Assuch, there exists a need in the art for a more efficient, economicaland systematic approach for the synthesis of novel materials and for thescreening of such materials for useful properties.

[0005] One of the processes whereby nature produces molecules havingnovel functions involves the generation of large collections (libraries)of molecules and the systematic screening of those libraries formolecules having a desired property. An example of such a process is thehumoral immune system which in a matter of weeks4 sorts through some10¹² antibody molecules to find one which specifically binds a foreignpathogen (Nisonoff, et al., The Antibody Molecule (Academic Press, NewYork, 1975)). This notion of generating and screening large libraries ofmolecules has recently been applied to the drug discovery process. Thediscovery of new drugs can be likened to the process of finding a keywhich fits a lock of unknown structure. One solution to the problem isto simply produce and test a large number of different keys in the hopethat one will fit the lock.

[0006] Using this logic, methods have been developed for the synthesisand screening of large libraries (up to 10¹⁴ molecules) of peptides,oligonucleotides and other small molecules. Geysen, et al., for example,have developed a method wherein peptide syntheses are carried out inparallel on several rods or pins (see, J. Immun. Meth. 102:259-274(1987), incorporated herein by reference for all purposes). Generally,the Geysen, er al. method involves functionalizing the termini ofpolymeric rods and sequentially immersing the termini in solutions ofindividual amino acids. In addition to the Geysen, et al. method,techniques have recently been introduced for synthesizing large arraysof different peptides and other polymers on solid surfaces. Pirrung, etal., have developed a technique for generating arrays of peptides andother molecules using, for example, light-directed,spatially-addressable synthesis techniques (see, U.S. Pat. No. 5,143,854and PCT Publication No. WO 90/15070, incorporated herein by referencefor all purposes). In addition, Fodor, et al. have developed, amongother things, a method of gathering fluorescence intensity data, variousphotosensitive protecting groups, masking techniques, and automatedtechniques for performing light-directed, spatially-addressablesynthesis techniques (see, Fodor, et al., PCT Publication No. WO92/10092, the teachings of which are incorporated herein by referencefor all purposes).

[0007] Using these various methods, arrays containing thousands ormillions of different elements can be formed (see, U.S. PatentApplication No. 805,727, filed Dec. 6, 1991, the teachings of which areincorporated herein by reference for all purposes). As a result of theirrelationship to semiconductor fabrication techniques, these methods havecome to be referred to as “Very Large Scale Immobilized PolymerSynthesis,” or “VLSIPS™” technology. Such techniques have met withsubstantial success in, for example, screening various ligands such aspeptides and oligonucleotides to determine their relative bindingaffinity to a receptor such as an antibody.

[0008] The solid phase synthesis techniques currently being used toprepare such libraries involve the stepwise, i.e., sequential, couplingof building blocks to form the compounds of interest. In the Pirrung, etal. method, for example, polypeptide arrays are synthesized on asubstrate by attaching photoremovable groups to the surface of thesubstrate, exposing selected regions of the substrate to light toactivate those regions, attaching an amino acid monomer with aphotoremovable group to the activated region, and repeating the steps ofactivation and attachment until polypeptides of the desired length andsequences are synthesized. These solid phase synthesis techniques, whichinvolve the sequential coupling of building blocks (e.g., amino acids)to form the compounds of interest, cannot readily be used to preparemany inorganic and organic compounds.

[0009] From the above, it is seen that a method and apparatus forsynthesizing and screening libraries of materials, such as inorganicmaterials, at known locations on a substrate is desired.

SUMMARY OF THE INVENTION

[0010] The present invention provides methods and apparatus for thepreparation and use of a substrate having an array of diverse materialsin predefined regions thereon. A substrate having an array of diversematerials thereon is prepared by delivering components of materials toPredefined regions on the substrate, and simultaneously reacting thecomponents to form at least two materials. Materials which can beprepared using the methods and apparatus of the present inventioninclude, for example, covalent network solids, ionic solids andmolecular solids. More particularly, materials which can be preparedinclude inorganic materials, intermetallic materials, metal alloys,ceramic materials, organic materials, organometallic materials,non-biological organic polymers, composite materials (e.g., inorganiccomposites, organic composites, or combinations thereof), etc. Onceprepared, these materials can be screened in parallel for usefulproperties including, for example, electrical, thermal, mechanical,morphological, optical, magnetic, chemical and other properties. Assuch, the present invention provides methods and apparatus for theparallel synthesis and analysis of novel materials having new and usefulproperties. Any material found to possess a useful property can besubsequently prepared on a large-scale.

[0011] In one embodiment of the present invention, a first component ofa first material is delivered to a first region on a substrate, and afirst component of a second material is delivered to a second region onthe same substrate. Thereafter, a second component of the first materialis delivered to the first region on the substrate, and a secondcomponent of the second material is delivered to the second region onthe substrate. The process is optionally repeated, with additionalcomponents, to form a vast array of components at predefined, i.e.,known, locations on the substrate. Thereafter, the components aresimultaneously reacted to form at least two materials. The componentscan be sequentially or simultaneously delivered to predefined regions onthe substrate in any stoichiometry, including a gradient ofstoichiometries, using any of a number of different delivery techniques.

[0012] In another embodiment of the present invention, a method isprovided for forming at least two different arrays of materials bydelivering substantially the same reaction components at substantiallyidentical concentrations to reaction regions on both first and secondsubstrates and, thereafter, subjecting the components on the firstsubstrate to a first set of reaction conditions and the components onthe second substrate to a second set of reaction conditions. Using thismethod, the effects of the various reaction parameters can be studied onmany materials simultaneously and, in turn, such reaction parameters canbe optimized. Reaction parameters which can be varied include, forexample, reactant amounts, reactant solvents, reaction temperatures,reaction times, the pressures at which the reactions are carried out,the atmospheres in which the reactions are conducted, the rates at whichthe reactions are quenched, the order in which the reactants aredeposited, etc.

[0013] In the delivery systems of the present invention, a small,precisely metered amount of each reactant component is delivered intoeach reaction region. This may be accomplished using a variety ofdelivery techniques, either alone or in combination with a variety ofmasking techniques. For example, thin-film deposition in combinationwith physical masking or photolithographic techniques can be used todeliver various reactants to selected regions on the substrate.Reactants can be delivered as amorphous films, epitaxial films, orlattice and superlattice structures. Moreover, using such techniques,reactants can be delivered to each site in a uniform distribution, or ina gradient of stoichiometries. Alternatively, the various reactantcomponents can be deposited into the reaction regions of interest from adispenser in the form of droplets or powder. Suitable dispensersinclude, for example, micropipettes, mechanisms adapted from ink-jetprinting technology, or electrophoretic pumps.

[0014] Once the components of interest have been delivered to predefinedregions on the substrate, they can be reacted using a number ofdifferent synthetic routes to form an array of materials. The componentscan be reacted using, for example, solution based synthesis techniques,photochemical techniques, polymerization techniques, template directedsynthesis techniques, epitaxial growth techniques, by the sol-gelprocess, by thermal, infrared or microwave heating, by calcination,sintering or annealing, by hydrothermal methods, by flux methods, bycrystallization through vaporization of solvent, etc. Thereafter, thearray can be screened for materials having useful properties.

[0015] In another embodiment of the present invention, an array ofinorganic materials on a single substrate at predefined regions thereonis provided. Such an array can consists of more than 10, 10², 10³, 10⁴,10⁵ or 10⁶ different inorganic compounds. It should be noted that whengradient libraries are prepared in each of the predefined reactionregions, a virtually infinite number of inorganic materials can beprepared on a single substrate. In some embodiments, the density ofregions per unit area will be greater than 0.04 regions/cm², morepreferably greater than 0.1 regions/cm², even more preferably greaterthan 1 region/cm², even more preferably greater than 10 regions/cm², andstill more preferably greater than 100 regions/cm². In most preferredembodiments, the density of regions per unit area will be greater than1,000 regions/cm², more preferably 10,000 regions/cm², even morepreferably greater than 100,000 regions/cm, and still more preferably10,000,000 regions/cm².

[0016] In yet another aspect, the present invention provides a materialhaving a useful property prepared by: forming an array of materials on asingle substrate; screening the array for a materials having a usefulproperty; and making additional amounts of the material having theuseful property. As such, the present invention provides methods andapparatus for the parallel synthesis and analysis of novel materialshaving new and useful properties.

[0017] A further understanding of the nature and advantages of theinventions herein may be realized by reference to the remaining portionsof the specification and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 illustrates an example of a reaction system employing aneight RF magnetron sputtering gun.

[0019]FIG. 2 illustrates masking of a substrate at a first location. Thesubstrate is shown in cross-section;

[0020] FIGS. 3A-3I illustrate the use of binary masking techniques togenerate an array of reactants on a single substrate;

[0021] FIGS. 4A-4I illustrate the use of physical masking techniques togenerate an array of reactants on a single substrate;

[0022] FIGS. 5A-5M illustrate the use of physical masking techniques togenerate an array of reactants on a single substrate;

[0023]FIG. 6 displays the elements of a typical guided droplet dispenserthat may be used to delivery the reactant solution of the presentinvention;

[0024]FIG. 7 illustrates an example of a Scanning RF SusceptibilityDetection System which can be used to detect the superconductivity of anarray of materials;

[0025]FIG. 8 is a map of the reactant components delivered to the 16predefined regions on the MgO substrate;

[0026]FIG. 8 is a photograph of the array of 16 different compounds onthe 1.25 cm×1.25 cm MgO substrate; and

[0027] FIGS. 10A-10B illustrate the resistance of the two conductingmaterials as a function of temperature.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS CONTENTS

[0028] I. Glossary

[0029] II. General Overview

[0030] III. Isolation of Reaction Regions on the Substrate

[0031] IV. Methods for Delivery of Reactant Components

[0032] A. Delivery Using Thin-Film Deposition Techniques

[0033] B. Delivery Using a Dispenser

[0034] V. Moving the Dispenser with Respect to the Substrate

[0035] VI. Synthetic Routes for Reacting the Array of Components

[0036] VII. Methods for Screening an Array of Materials

[0037] VIII. Alternative Embodiments

[0038] IX. Examples

[0039] A. Synthesis of an Array of Copper Oxide Thin-Film Materials

[0040] B. Synthesis of an Array of 16 Different Organic Polymers

[0041] C. Synthesis of an Array of Different Zeolites

[0042] D. Synthesis of an Array of Copper Oxide Compounds Using SprayingDeposition Techniques

[0043] E. Synthesis of an Array of Manganese Oxide Thin-Film Materials

[0044] X. Conclusion

[0045] I. Glossary

[0046] The following terms are intended to have the following generalmeanings as they are used herein.

[0047] 1. Substrate: A material having a rigid or semi-rigid surface. Inmany embodiments, at least one surface of the substrate will besubstantially flat, although in some embodiments it may be desirable tophysically separate synthesis regions for different materials with, forexample, dimples, wells, raised regions, etched trenches, or the like.In some embodiments, the substrate itself contains wells, raisedregions, etched trenches, etc. which form all or part of the synthesisregions. According to other embodiments, small beads or pellets may beprovided on the surface within dimples or on other regions of thesurface or, alternatively, the small beads or pellets may themselves bethe substrate.

[0048] 2. Predefined Region: A predefined region is a localized area ona substrate which is, was, or is intended to be used for formation of aselected material and is otherwise referred to herein in the alternativeas “known” region, “reaction” region, a “selected” region, or simply a“region.” The predefined region may have any convenient shape, e.g.,circular, rectangular, elliptical, wedge-shaped, etc. Additionally, thepredefined region, i.e., the reaction site, can be a bead or pelletwhich is coated with a reactant component(s) of interest. In thisembodiment, the bead or pellet can be identified with a tag, such as anetched binary bar code that can be used to indicate the history of thebead or pellet, i.e., to identify which components were depositedthereon. In some embodiments, a predefined region and, therefore, thearea upon which each distinct material is synthesized is smaller thanabout 25 cm², preferably less than 10 cm², more preferably less than 5cm¹, even more preferably less than 1 cm², still more preferably lessthan 1 mm², and even more preferably less than 0.5 mm². In mostpreferred embodiments, the regions have an area less than about 10,000cm², preferably less than 1,000 μm², more preferably less than 100 μm²,and even more preferably less than 10 cm².

[0049] 3. Radiation: Energy which may be selectively applied includingenergy having a wavelength between 10⁻¹⁴ and 10⁴ meters including, forexample, electron beam radiation, gamma radiation, x-ray radiation,ultraviolet radiation, visible light, infrared radiation, microwaveradiation and radio waves. “Irradiation” refers to the application ofradiation to a surface.

[0050] 4. Component: “Component” is used herein to refer to each of theindividual chemical substances that act upon one another to produce aparticular material and is otherwise referred to herein in thealternative as “reactant” or “reactant component.” That is to say, thecomponents or, alternatively, reactants are the molecules that act uponone another to produce a new molecule(s), i.e., product(s); for example,in the reaction HCl+NaO→NaCl+H₂O, the HCl and the NaOH are thecomponents or reactants.

[0051] 5. Material: The term “material” is used herein to refer tosolid-state compounds, extended solids, extended solutions, clusters ofmolecules or atoms, crystals, etc.

[0052] 6. Covalent Network Solids: Solids that consist of atoms heldtogether in a large network of chains by covalent bonds. Such covalentnetwork solids include, but are not limited to, diamond, siliconnitride, graphite, bunkmisterfullerene and organic polymers which cannotbe synthesized in a stepwise fashion.

[0053] 7. Ionic Solids: Solids which can be modeled as cations andanions held together by electrical attraction of opposite charge. Suchionic solids include, but are not restricted to, CaF₂, CdCl₂, ZnCl₂,⁻NaCl₂, AgF, AgCl, AgBr and spinels (e.g., ZnAl₂O₄, MgAl₂O₄, FrCr₂O₄,etc.).

[0054] 8. Molecular Solids: Solids consisting of atoms or molecules heldtogether by intermolecular forces. Molecular solids include, but are notlimited to, extended solids, solid neon, organic compounds, synthetic ororganic metals (e.g., tetrathiafulvalene-tetracyanoquinonedimethane(TTF-TCNQ)), liquid crystals (e.g., cyclic siloxanes) and proteincrystals.

[0055] 9. Inorganic Materials: Materials which do not contain carbon asa principal element. The oxides and sulphides of carbon and the metalliccarbides are considered inorganic materials. Examples of inorganiccompounds which can be synthesized using the methods of the presentinvention include, but are not restricted to, the following:

[0056] (a) Intermetallics (or Intermediate Constituents): Intermetalliccompounds constitute a unique class of metallic materials that formlong-range ordered crystal structures below a critical temperature. Suchmaterials form when atoms of two metals combine in certain proportionsto form crystals with a different structure from that of either of thetwo metals (e.g., NiAl, CrBc₂, CuZn, etc.).

[0057] (b) Metal Alloys: A substance having metallic properties andwhich is composed of a mixture of two or more chemical elements of whichat least one is a metal.

[0058] (c) Magnetic Alloys: An alloy exhibiting ferromagnetism such assilicon iron, but also iron-nickel alloys, which may contain smallamounts of any of a number of other elements (e.g., copper, aluminum,chromium, molybdenum, vanadium, etc.), and iron-cobalt alloys.

[0059] (d) Ceramics: Typically, a ceramic is a metal oxide, boride,carbide, nitride, or a mixture of such materials. In addition, ceramicsare inorganic, nonmetallic products that are subjected to hightemperatures (i.e., above visible red, 540° C. to 1000° C.) duringmanufacture or use. Such materials include, for example, alumina,zirconium, silicon carbide, aluminum nitride, silicon nitride, theYBaCu₃O⁷⁻⁸ superconductor, ferrite (BaFe₁₂O₁₉), Zeolite A(Na₁₂[(SiO₂)₁₂(AlO₂)].27H₂O), soft and permanent magnets, etc. Hightemperature superconductors are illustrative of materials that can beformed and screened using the present invention. “High temperaturesuperconductors” include, but are not restricted to, theLa_(2−x)Sr_(x)CuO₄ superconductors, the Bi₂CaSr₂Cu₂O_(8+x)superconductors, the Ba_(1−x)BiO₃ superconductors and the ReBaCusuperconductors. Such high temperature superconductors will, when theyhave the desired properties, have critical temperatures above 30° K,preferably above 50° K, and more preferably above 70° K.

[0060] 10. Organic Materials: Compounds, which generally consist ofcarbon and hydrogen, with or without oxygen, nitrogen or other elements,except those in which carbon does not play a critical role (e.g.,carbonate salts). Examples of organic materials which can be synthesizedusing the methods of the present invention include, but are notrestricted to, the following: (a) Non-biological, organic polymers:Nonmetallic materials consisting of large macromolecules composed ofmany repeating units. Such materials can be either natural or synthetic,cross-linked or non-crosslinked, and they may be homopolymers,copolymers, or higher-ordered polymers (e.g., terpolymers, etc.). By“non-biological,” α-amino acids and nucleotides are excluded. Moreparticularly, “non-biological, organic polymers” exclude those polymerswhich are synthesized by a linear, stepwise coupling of building blocks.Examples of polymers which can be prepared using the methods of thepresent invention include, but are not limited to, the following:polyurethanes, polyesters, polycarbonates, polyethyleneimines,polyacetates, polystyrenes, polyamides, polyanilines, polyacetylenes,polypyrroles, etc.

[0061] 11. Organometallic Materials: A class of compounds of the typeR-M, wherein carbon atoms are linked directly with metal atoms (e.g.,lead tetraethyl (Pb(C₂H₅)₄), sodium phenyl (C₆H₅.Na), zinc dimethyl(Zn(CH₃)₇), etc.).

[0062] 12. Composite Materials: Any combination of two materialsdiffering in form or composition on a macroscale. The constituents ofcomposite materials retain their identities, i.e., they do not dissolveor merge completely into one another although they act in concert. Suchcomposite materials may be inorganic, organic or a combination thereof.Included within this definition are, for example, doped materials,dispersed metal catalysts and other heterogeneous solids.

[0063] II. General Overview

[0064] The present invention provides methods and apparatus for thepreparation and use of a substrate having an array of materials inpredefined regions thereon. The invention is described herein primarilywith regard to the preparation of inorganic materials, but can readilybe applied in the preparation of other materials. Materials which can beprepared in accordance with the methods of the present inventioninclude, for example, covalent network solids, ionic solids andmolecular solids. More particularly, materials which can be prepared inaccordance with the methods of the present invention include, but arenot limited to, inorganic materials, intermetallic materials, metalalloys, ceramic materials, organic materials, organometallic materials,non-biological organic polymers, composite materials (e.g., inorganiccomposites, organic composites, or combinations thereof), or othermaterials which will be apparent to those of skill in the art uponreview of this disclosure.

[0065] The resulting substrate having an array of materials thereon willhave a variety of uses. For example, once prepared, the substrate can bescreened for materials having useful properties. Accordingly, the arrayof materials is preferably synthesized on a single substrate. Bysynthesizing the array of materials on a single substrate, screening thearray for materials having useful properties is more easily carried out.Alternatively, however, the array of materials can be synthesized on aseries of beads or pellets by depositing on each bead or pellet thecomponents of interest. In this embodiment, each bead or pellet willhave a tag which indicates the history of components deposited thereonas well as their stoichiometries. The tag can, for example, be a binarytag etched into the surface of the bead so that it can be read usingspectroscopic techniques. As with the single substrate having an arrayof materials thereon, each of the individual beads or pellets can bescreened for useful properties.

[0066] Properties which can be screened for include, for example,electrical, thermal mechanical, morphological, optical, magnetic,chemical, etc. More particularly, properties which can be screened forinclude, for example, conductivity, super-conductivity, resistivity,thermal conductivity, anisotropy, hardness, crystallinity, opticaltransparency, magnetoresistance, permeability, frequency doubling,photoemission, coercivity, critical current, or other useful propertieswhich will be apparent to those of skill in the art upon review of thisdisclosure. Importantly, the synthesizing and screening of a diversearray of materials enables new compositions with new physical propertiesto be identified. Any material found to possess a useful property can besubsequently prepared on a large-scale. It will be apparent to those ofsill in the art that once identified using the methods of the presentinvention, a variety of different methods can be used to prepare suchuseful materials on a large or bulk scale with essentially the samestructure and properties.

[0067] Generally, the array of materials is prepared by successivelydelivering components of materials to predefined regions on a substrate,and simultaneously reacting the components to form at least twomaterials. In one embodiment, for example, a first component of a firstmaterial is delivered to a first region on a substrate, and a firstcomponent of a second material is delivered to a second region on thesame substrate. Thereafter, a second component of the first material isdelivered to the first regions on the substrate, and a second componentof the second material is delivered to the second region on thesubstrate. Each component can be delivered in either a uniform orgradient fashion to produce either a single stoichiometry or,alternatively, a large number of stoichiometries within a singlepredefined region. Moreover, reactants can be delivered as amorphousfilms, epitaxial films, or lattice or superlattice structures. Theprocess is repeated, with additional components, to form a vast array ofcomponents at predefined, i.e., known, locations on the substrate.Thereafter, the components are simultaneously reacted to form at leasttwo materials. As explained hereinbelow, the components can besequentially or simultaneously delivered to predefined regions on thesubstrate using any of a number of different delivery techniques.

[0068] In the methods of the present invention, the components, afterbeing delivered to predefined regions on the substrate, can be reactedusing a number of different synthetic routes. For example, thecomponents can be reacted using, for example, solution based synthesistechniques, photochemical techniques, polymerization techniques,template directed synthesis techniques, epitaxial growth techniques, bythe sol-gel process, by thermal, infrared or microwave heating, bycalcination, sintering or annealing, by hydrothermal methods, by fluxmethods, by crystallization through vaporization of solvent, etc. Otheruseful synthesis techniques that can be used to simultaneously react thecomponents of interest will be readily apparent to those of skill in theart.

[0069] Since the reactions are conducted in parallel, the number ofreaction steps can be ed. Moreover, the reaction conditions at differentreaction regions can be controlled independently. As such, reactantamounts, reactant solvents, reaction temperatures, reaction times, therates at which the reactions are quenched, deposition order ofreactants, etc. can be varied from reaction region to reaction region onthe substrate. Thus, for example, the first component of the firstmaterial and the first component of the second material can be the sameor different. If the first component of the first material is the sameas the first component of the second materials, this component can beoffered to the first and second regions on the substrate at either thesame or different concentrations. This is true as well for the secondcomponent of the first material and the second component of the secondmaterial, etc. As with the first component of the first and secondmaterials, the second component of the first material and the secondcomponent of the second material can be the same or different and, ifthe same, this component can be offered to the first and second regionson the substrate at either the same or different concentrations.Moreover, within a given predefined region on the substrate, thecomponent can be delivered in either a uniform or gradient fashion. Ifthe same components are delivered to the first and second regions of thesubstrate at identical concentrations, then the reaction conditions(e.g., reaction temperatures, reaction times, etc.) under which thereactions are carried out can be varied from reaction region to reactionregion.

[0070] Moreover, in one embodiment of the present invention, a method isprovided for forming at least two different arrays of materials bydelivering substantially the same reactant components at substantiallyidentical concentrations to reaction regions on both first and secondsubstrates and, thereafter, subjecting the components on the firstsubstrate to a first set of reaction conditions and the components onthe second substrate to a second set of reaction conditions in a widearray of compositions. Using this method, the effects of the variousreaction parameters can be studied and, in turn, optimized. Reactionparameters which can be varied include, for example, reactant amounts,reactant solvents, reaction temperatures, reaction times, the pressuresat which the reactions are carried out, the atmospheres in which thereactions are conducted, the rates at which the reactions are quenched,the order in which the reactants are deposited, etc. Other reactionparameters which can be varied will be apparent to those of skill in theart.

[0071] The reactant components in the individual reaction regions mustoften be prevented from moving to adjacent reaction regions. Mostsimply, this can be ensured by leaving a sufficient amount of spacebetween the regions on the substrate so that the various componentscannot interdiffuse between reaction regions. Moreover, this can beensured by providing an appropriate barrier between the various reactionregions on the substrate. In one approach, a mechanical device orphysical structure defines the various regions on the substrate. A wallor other physical barrier, for example, can be used to prevent thereactant components in the individual reaction regions from moving toadjacent reaction regions. This wall or physical barrier may be removedafter the synthesis is carried out. One of skill in the art willappreciate that, at times, it may be beneficial to remove the wall orphysical barrier before screening the array of materials.

[0072] In another approach, a hydrophobic material, for example, can beused to coat the region surrounding the individual reaction regions.Such materials prevent aqueous (and certain other polar) solutions frommoving to adjacent reaction regions on the substrate. Of course, whennon-aqueous or nonpolar solvents are employed, different surfacecoatings will be required. Moreover, by choosing appropriate materials(e.g., substrate material, hydrophobic coatings, reactant solvents,etc.), one can control the contact angle of the droplet with respect tothe substrate surface. Large contact angles are desired because the areasurrounding the reaction region remains unwetted by the solution withinthe reaction region.

[0073] In the delivery systems of the present invention, a small,precisely metered amount of each reactant component is delivered intoeach reaction region. This may be accomplished using a variety ofdelivery techniques, either alone or in combination with a variety ofmasking techniques. For example, thin-film deposition techniques incombination with physical masking or photolithographic techniques can beused to deliver the various reactants to selected regions on thesubstrate. More particularly, sputtering systems, spraying techniques,laser ablation techniques, electron beam or thermal evaporation, ionimplantation or doping techniques, chemical vapor deposition (CVD), aswell as other techniques used in the fabrication of integrated circuitsand epitaxially grown materials can be applied to deposit highly uniformlayers of the various reactants on selected regions of the substrate.Alternatively, by varying the relative geometries of the mask, targetand/or substrate, a gradient of components can be deposited within eachpredefined regions on the substrate or, alternatively, over all of thepredefined regions on the substrate. Such thin-film depositiontechniques are generally used in combination with masking techniques toensure that the reactant components are being delivered only to thereaction regions of interest.

[0074] Moreover, in addition to the foregoing, the various reactantcomponents can be deposited into the reaction regions of interest from adispenser in the form of droplets or powder. Conventional micropipettingapparatus can, for example, be adapted to dispense droplet volumes of 5nanoliters or smaller from a capillary. Such droplets can fit within areaction region having a diameter of 300 μm or less when a mask isemployed. The dispenser can also be of the type employed in conventionalink-jet printers. Such ink-jet dispenser systems include, for example,the pulse pressure type dispenser system, the bubble jet type dispensersystem and the slit jet type dispenser system. These ink-jet dispensersystems are able to deliver droplet volumes as small as 5 picoliters.Moreover, such dispenser systems can be manual or, alternatively, theycan be automated using, for example, robotics techniques.

[0075] The dispenser of the present invention can be aligned withrespect to the appropriate reaction regions by a variety of conventionalsystems. Such systems, which are widely used in the microelectronicdevice fabrication and testing arts, can deliver droplets to individualreaction regions at rates of up to 5,000 drops per second. Thetranslational (X-Y) accuracy of such systems is well within 1 μm. Theposition of the dispenser stage of such systems can be calibrated withrespect to the position of the substrate by a variety of methods knownin the art. For example, with only one or two reference points on thesubstrate surface, a “dead reckoning” method can be provided to locateeach reaction region of the array. The reference marks in any suchsystems can be accurately identified by using capacitive, resistive oroptical sensors. Alternatively, a “vision” system employing a camera canbe employed.

[0076] In another embodiment of the present invention, the dispenser canbe aligned with respect to the reaction region of interest by a systemanalogous to that employed in magnetic and optical storage media fields.For example, the reaction region in which the component is to bedeposited is identified by its track and sector location on the disk.The dispenser is then moved to the appropriate track while the disksubstrate rotates. When the appropriate reaction region is positionedbelow the dispenser, a droplet of reactant solution is released.

[0077] In some embodiments, the reaction regions may be further definedby dimples in the substrate surface. This will be especiallyadvantageous when a head or other sensing device must contact or glidealong the substrate surface. The dimples may also act as identificationmarks directing the dispenser to the reaction region of interest.

[0078] III. Isolation of Reaction Regions on a Substrate

[0079] In a preferred embodiment, the methods of the present inventionare used to prepare an array of diverse materials at known locations ona single substrate surface. Essentially, any conceivable substrate canbe employed in the invention. The substrate can be organic, inorganic,biological, nonbiological, or a combination of any of these, existing asparticles, strands, precipitates, gels, sheets, tubing, spheres,containers, capillaries, pads, slices, films, plates, slides, etc. Thesubstrate can have any convenient shape, such a disc, square, sphere,circle, etc. The substrate is preferably flat, but may take on a varietyof alternative surface configurations. For example, the substrate maycontain raised or depressed regions on which the synthesis of diversematerials takes place. The substrate and its surface preferably form arigid support on which to carry out the reaction described herein. Thesubstrate may be any of a wide variety of materials including, forexample, polymers, plastics, pyrex, quartz, resins, silicon, silica orsilica-based materials, carbon, metals, inorganic glasses, inorganiccrystals, membranes, etc. Other substrate materials will be readilyapparent to those of skill in the art upon review of this disclosure.Surfaces on the solid substrate can be composed of the same materials asthe substrate or, alternatively, they can be different, i.e., thesubstrates can be coated with a different material. Moreover, thesubstrate surface can contain thereon an adsorbent (for example,cellulose) to which the components of interest are delivered. The mostappropriate substrate and substrate-surface materials will depend on theclass of materials to be synthesized and the selection in any given casewill be readily apparent to those of skill in the art.

[0080] In some embodiments, a predefined region on the substrate and,therefore, the area upon which each distinct material is synthesized issmaller than about 25 cm², preferably less than 10 cm², more preferablyless than 5 cm², even more preferably 1 cm², still more preferably lessthan 1 mm², and still more preferably less than 0.5 mm². In mostpreferred embodiments, the regions have an area less than about 10,000μm², preferably less than 1,000 μm², more preferably less than 100 μm²,and even more preferably less than 10 μm².

[0081] In preferred embodiments, a single substrate has at least 10different materials and, more preferably, at least 100 differentmaterials synthesized thereon. In even more preferred embodiments, asingle substrate has more than 10³, 10⁴, 10⁵, 10⁶, or more materialssynthesized thereon. In some embodiments, the delivery process isrepeated to provide materials with as few as two components, althoughthe process may be readily adapted to form materials having 3, 4, 5, 6,7, 8 or more components therein. The density of regions per unit areawill be greater than 0.04 regions/cm², more preferably greater than 0.1regions/cm², even more preferably greater than 1 region/cm², even morepreferably greater than 10 regions/cm², and still more preferablygreater than 100 regions/cm². In most preferred embodiments, the densityof regions per unit area will be greater than 1,000 regions/cm², morepreferably 10,000 regions/cm², even more preferably greater than 100,000regions/cm², and still more preferably 10,000,000 regions/cm².

[0082] In other embodiments, the substrate can be a series of smallbeads or pellets (hereinafter “beads”). The number of beads used willdepend on the number of materials to be synthesized and can rangeanywhere from 2 to an infinite number of beads. In this embodiment, eachof the beads is uniformly coated with the reactant component(s) ofinterest and, thereafter, reacted. This is readily done, for example, byusing a series of vessels each of which contains a solution of aparticular reactant component. The beads are equally divided into groupscorresponding to the number of components used to generate the array ofmaterials. Each group of beads is then added to one of the vesselswherein a coating of one of the components in solution forms on thesurface of each bead. The beads are then pooled together into one groupand heated to produce a dry component layer on the surface of each ofthe beads. The process is repeated several times to generate an array ofdifferent reaction components on each of the beads. Once the componentsof interest have been deposited on the beads, the beads are reacted toform an array of materials. All of the beads may or may not be reactedunder the same reaction conditions. To determine the history of thecomponents deposited on a particular bead, mass spectroscopic techniquescan be used. Alternatively, each bead can have a tag which indicates thehistory of components deposited thereon as well as theirstoichiometries. The tag can be, for example, a binary tag etched intothe surface of the bead so that it can be read using spectroscopictechniques. As with the single substrate having an array of materialsthereon, each of the individual beads or pellets can be screened formaterials having useful properties.

[0083] More particularly, if an array of materials is to be generatedbased on Bi, Cu, Ca and Si using a series of beads as the substrate, forexample, four vessels containing aqueous solutions of Bi(NO₃)₃,Cu(NO₃)₃, Ca(NO₃)₃ and Si(NO₃)₃ would be employed. A portion of thebeads are added to the vessel containing the Bi(NO₃)₃ solution; aportion of the beads are added to the Cu(NO)₃ solution; a portion of thebeads are added to the vessel containing the Ca(NO₃)₃ solution; and,finally, a portion of the beads are added to the vessel containing theSi(NO₃ solution. Once the beads are uniformly coated with the componentcontained in the vessel, the beads are removed from the vessel, dried,etched, pooled together into one group and, thereafter, subsequentlydivided and added to the vessels containing the foregoing reactantcomponents of interest. The process is optionally repeated, withadditional components, to form a vast array of components on each of thebeads. It will be readily apparent to those of skill in the art that anumber of variations can be made to this technique to generate a vastarray of beads containing a vast array of components thereon. Forexample, some of the beads can be coated with only two components,others with more than two components. Additionally, some of the beadscan be coated two or more times with the same components, whereas otherbeads are coated a single time with a given component.

[0084] As previously explained, the substrate is preferably flat, butmay take on a variety of alternative surface configurations. Regardlessof the configuration of the substrate surface, it is imperative that thereactant components in the individual reaction regions be prevented frommoving to adjacent reaction regions. Most simply, this can be ensured byleaving a sufficient amount of space between the regions on thesubstrate so that the various components cannot interdiffuse betweenreaction regions. Moreover, this can be ensured by providing anappropriate barrier between the various reaction regions on thesubstrate. A mechanical device or physical structure can be used todefine the various regions on the substrate. For example, a wall orother physical barrier can be used to prevent the reactant components inthe individual reaction regions from moving to adjacent reactionregions. Alternatively, a dimple or other recess can be used to preventthe reactant components in the individual reaction regions from movingto adjacent reaction regions.

[0085] If the substrate used in the present invention is to containdimples or other recesses, the dimples must be sufficiently small toallow close packing on the substrate. Preferably, the dimples will beless than 1 mm in diameter, preferably less than 0.5 mm in diameter,more preferably less than 10,000 μm in diameter, even more preferablyless than 100 μm in diameter, and still more preferably less than 25 μmin diameter. The depth of such dimples will preferably be less than 100μm and more preferably less than 25 μm below the upper surface of thesubstrate.

[0086] Dimples having these characteristics can be produced by a varietyof techniques including laser, pressing, or etching techniques. Asuitable dimpled substrate surface can, for example, be provided bypressing the substrate with an imprinted “master” such as those commonlyused to prepare compact optical disks. In addition, an isotropic oranisotropic etching technique employing photolithography can beemployed. In such techniques, a mask is used to define the reactionregions on the substrate. After the substrate is irradiated through themask, selected regions of the photoresist are removed to define thearrangement of reaction regions on the substrate. The dimples may be cutinto the substrate with standard plasma or wet etching techniques. Ifthe substrate is a glass or silicon material, suitable wet etchmaterials can include hydrogen fluoride, or other common wet etchantsused in the field of semiconductor device fabrication. Suitable plasmaetchants commonly used in the semiconductor device fabrication field canalso be employed. Such plasma etchants include, for example, mixtures ofhalogen containing gases and inert gases. Typically, a plasma etch willproduce dimples having a depth of less than 10 μm, although depths of upto 50 μm may be obtained under some conditions.

[0087] Another method for preparing a suitably dimpled surface employsphotochemically etchable glass or polymer sheets. For example, aphotochemically etchable glass known as “FOTOFORM” is available fromCorning Glass Company (New York). Upon exposure to radiation through amask, the glass becomes soluble in aqueous solutions. Thereafter, theexposed glass is simply washed with the appropriate solution to form thedimpled surface. With this material, well-defined dimples can be madehaving aspect ratios of 10 to 1 (depth to diameter) or greater, anddepths of up to 0.1 inches. Dimple diameters can be made as small as 25μm in a 250 μm thick glass layer. Moreover, the dimpled surface cancontain thereon an adsorbent (for example, cellulose) to which thecomponents of interest are delivered.

[0088] Even when a dimpled surface is employed, it is often important toensure that the substrate material is not wetted beyond the reactionregion parameters. Most simply, this can be ensured by leaving asufficient amount of space between the regions on the substrate so thatthe various components cannot interdiffuse between reaction regions. Inaddition, other techniques can be applied to control the physicalinteractions that affect wetting, thereby ensuring that the solutions inthe individual reaction regions do not wet the surrounding surface andcontaminate other reaction regions. Whether or not a liquid droplet willwet a solid surface is governed by three tensions: the surface tensionat the liquid-air interface, the interfacial tension at the solid-liquidinterface and the surface tension at the solid-air interface. If the sumof the liquid-air and liquid-solid tensions is greater than thesolid-air tension, the liquid drop will form a bead (a phenomenon knownas “lensing”). If, on the other hand, the sum of the liquid-air andliquid-solid tensions is less than the solid-air tension, the drop willnot be confined to a given location, but will instead spread over thesurface. Even if the surface tensions are such that the drop will notspread over the surface, the contact or wetting angle (i.e., the anglebetween the edge of the drop and the solid substrate) may besufficiently small that the drop will cover a relatively large area(possibly extending beyond the confines of a given reaction region).Further, small wetting angles can lead to formation of a thin(approximately 10 to 20 Å) “precursor film” which spreads away from theliquid bead. Larger wetting angles provide “taller” beads that take upless surface area on the substrate and do not form precursor films.Specifically, if the wetting angle is greater than about 90°, aprecursor film will not form.

[0089] Methods for controlling chemical compositions arid, in turn, thelocal surface free energy of a substrate surface include a variety oftechniques apparent to those in the art. Chemical vapor deposition andother techniques applied in the fabrication of integrated circuits canbe applied to deposit highly uniform layers on selected regions of thesubstrate surface. If, for example, an aqueous reactant solution isused, the region inside the reaction regions may be hydrophilic, whilethe region surrounding the reaction regions may be hydrophobic. As such,the surface chemistry can be varied from position to position on thesubstrate to control the surface free energy and, in turn, the contactangle of the drops of reactant solution. In this manner, an array ofreaction regions can be defined on the substrate surface.

[0090] Moreover, as previously explained, the reactant components in theindividual reaction regions can be prevented from moving to adjacentreaction regions by leaving a sufficient amount of space between theregions on the substrate so that the various components cannotinterdiffuse between reaction regions.

[0091] IV. Methods for Delivery of Reactant Components

[0092] In the delivery systems of the present invention, a small,precisely metered amount of each reactant component is delivered intoeach reaction region. This may be accomplished using a variety ofdelivery techniques, either alone or in combination with a variety ofphysical masking or photolithographic techniques. Delivery techniqueswhich are suitable for use in the methods of the present invention cangenerally be broken down into those involving the use of thin-filmdeposition techniques and those involving the use of a dispenser.

[0093] A. Delivery Using Thin-Film Deposition Techniques

[0094] Thin-film deposition techniques in combination with physicalmasking or photolithographic techniques can be used to depositthin-films of the various reactants on predefined regions on thesubstrate. Such thin-film deposition techniques can generally be brokendown into the following four categories: evaporative methods,glow-discharge processes, gas-phase chemical processes, and liquid-phasechemical techniques. Included within these categories are, for example,sputtering techniques, spraying techniques, laser ablation techniques,electron beam or thermal evaporation techniques, ion implantation ordoping techniques, chemical vapor deposition techniques, as well asother techniques used in the fabrication of integrated circuits. All ofthese techniques can be applied to deposit highly uniform layers, i.e.,thin-films, of the various reactants on selected regions on thesubstrate. Moreover, by adjusting the relative geometries of the masks,the delivery source and/or the substrate, such thin-film depositiontechniques can be used to generate uniform gradients at each reactionregion on the substrate or, alternatively, over all of the reactionregions on the substrate. For an overview of the various thin-filmdeposition techniques which can be used in the methods of the presentinvention, see, for example, Handbook of Thin-Film Deposition Processesand Techniques, Noyes Publication (1988), which is incorporated hereinby reference for all purposes.

[0095] Thin-films of the various reactants can be deposited on thesubstrate using evaporative methods in combination with physical maskingtechniques. Generally, in thermal evaporation or vacuum evaporationmethods, the following sequential steps take place: (1) a vapor isgenerated by boiling or subliming a target material; (2) the vapor istransported from the source to the substrate; and (3) the vapor iscondensed to a solid film on the substrate surface. Evaporants, i.e.,target materials, which can be used in the evaporative methods cover anextraordinary range of varying chemical reactivity and vapor pressuresand, thus, a wide variety of sources can be used to vaporize the targetmaterial. Such sources include, for example, resistance-heatedfilaments, electron beams; crucible heated by conduction, radiation orrf-inductions; arcs, exploding wires and lasers. In preferredembodiments of the present invention, thin-film deposition usingevaporative methods is carried out using lasers, filaments, electronbeams or ion beams as the source. Successive rounds of deposition,through different physical masks, using evaporative methods generates anarray of reactants on the substrate for parallel synthesis.

[0096] Molecular Beam Epitaxy (MBE) is an evaporative method that can beused to grow epitaxial thin-films. In this method, the films are formedon single-crystal substrates by slowly evaporating the elemental ormolecular constituents of the film from separate Knudsen effusion sourcecells (deep crucibles in furnaces with cooled shrouds) onto substratesheld at temperatures appropriate for chemical reaction, epitaxy andre-evaporation of excess reactants. The furnaces produce atomic ormolecular beams of relatively small diameter, which are directed at theheated substrate, usually silicon or gallium arsenide. Fast shutters areinterposed between the sources and the substrates. By controlling theseshutters, one can grow superlattices with precisely controlleduniformity, lattice match, composition, dopant concentrations, thicknessand interfaces down to the level of atomic layers.

[0097] In addition to evaporative methods, thin-films of the variousreactants can be deposited on the substrate using glow-dischargeprocesses in combination with physical masking techniques. The mostbasic and well known of these processes is sputtering, i.e., theejection of surface atoms from an electrode surface by momentum transferfrom bombarding ions to surface atoms. Sputtering or sputter-depositionis a term used by those of skill in the art to cover a variety ofprocesses. One such process is RF/DC Glow Discharge Plasma Sputtering.In this process, a plasma of energized ions is created by applying ahigh RF or DC voltage between a cathode and an anode. The energized ionsfrom the plasma bombard the target and eject atoms which then deposit ona substrate. Ion-Beam Sputtering is another example of a sputteringprocess which can be used to deposit thin-films of the various reactantcomponents on the substrate. Ion-Beam Sputtering is similar to theforegoing process except the ions are supplied by an ion source and nota plasma. It will be apparent to one of skill in the art that othersputtering techniques (e.g., diode sputtering, reactive sputtering,etc.) and other glow-discharge processes can be used to depositthin-films on a substrate. Successive rounds of deposition, throughdifferent physical masks, using sputtering or other glow-dischargetechniques generates an array of reactants on the substrate for parallelsynthesis.

[0098] An example of an eight RF magnetron sputtering gun system whichcan be employed in the methods of the present invention is illustratedin FIG. 1. This system comprises eight RF magnetron sputtering guns 110,each of which contains a reactant component of interest. The eight RFmagnetron sputtering guns are located about 3 to about 4 inches above adisk 112 containing thereon eight masking patterns 114 as well as eightfilm-thickness monitors 116. In this system, the eight RF magnetronsputtering guns as well as the disk are fixed. The substrate 118,however, is coupled to a substrate manipulator 120 which is capable oflinear and rotational motion and which engages the substrate with theparticular mask of interest so that the substrate is in contact with themask when the sputtering begins. Combinations of the eight componentsare generated on the substrate by the sequential deposition of eachcomponent through its respective mask. This entire system is used invacuo.

[0099] In addition to evaporative methods and sputtering techniques,thin-films of the various reactants can be deposited on the substrateusing Chemical Vapor Deposition (CVD) techniques in combination withphysical masking techniques. CVD involves the formation of stable solidsby decomposition of gaseous chemicals using heat, plasma, ultraviolet,or other energy source, of a combination of sources. Photo-Enhanced CVD,based on activation of the reactants in the gas or vapor phase byelectromagnetic radiation, usually short-wave ultraviolet radiation, andPlasma-Assisted CVD, based on activation of the reactants in the gas orvapor phase using a plasma, are two particularly useful chemical vapordeposition techniques. Successive rounds of deposition, throughdifferent physical masks, using CVD techniques generates an array ofreactants on the substrate for parallel synthesis.

[0100] In addition to evaporative methods, sputtering and CVD,thin-films of the various reactants can be deposited on the substrateusing a number of different mechanical techniques in combination withphysical masking techniques. Such mechanical techniques include, forexample, spraying, spinning, dipping, and draining, flow coating, rollercoating, pressure-curtain coating, brushing, etc. Of these, the spray-onand spin-on techniques are particularly useful. Sprayers which can beused to deposit thin-films include, for example, ultrasonic nozzlesprayers, air atomizing nozzle sprayers and atomizing nozzle sprayers.In ultrasonic sprayers, disc-shaped ceramic piezoelectric transducerscovert electrical energy into mechanical energy. The transducers receiveelectrical input in the form of a high-frequency signal from a powersupply that acts as a combination oscillator/amplifier. In air atomizingsprayers, the nozzles intermix air and liquid streams to produce acompletely atomized spray. In atomizing sprayers, the nozzles use theenergy of from a pressurized liquid to atomize the liquid and, in turn,produce a spray. Successive rounds of deposition, through differentphysical masks, using mechanical techniques such as spraying generatesan array of reactants on the substrate for parallel synthesis.

[0101] In addition to the foregoing techniques, photolithographictechniques of the type known in the semiconductor industry can be used.For an overview of such techniques, see, for example, Sze, VLSITechnology, McGraw-Hill (1983) and Mead, et al., Introduction to VLSISystems, Addison-Wesley (1980), which are incorporated herein byreference for all purposes. A number of different photolithographictechniques known to those of skill in the art can be used. In oneembodiment, for example, a photoresist is deposited on the substratesurface; the photoresist is selectively exposed, i.e., photolyzed; thephotolyzed or exposed photoresist is removed; a reactant is deposited onthe exposed regions on the substrate; and the remaining unphotolyzedphotoresist is removed. Alternatively, when a negative photoresist isused, the photoresist is deposited on the substrate surface; thephotoresist is selectively exposed, i.e., photolyzed; the unphotolyzedphotoresist is removed; a reactant is deposited on the exposed regionson the substrate; and the remaining photoresist is removed. In anotherembodiment, a reactant is deposited on the substrate using, for example,spin-on or spin-coating techniques; a photoresist is deposited on top ofthe reactant; the photoresist is selectively exposed, i.e., photolyzed;the photoresist is removed from the exposed regions; the exposed regionsare etched to remove the reactant from those regions; and the remainingunphotolyzed photoresist is removed. As with the previous embodiment, anegative photoresist can be used in place of the positive photoresist.Such photolithographic techniques can be repeated to produce an array ofreactants on the substrate for parallel synthesis.

[0102] Using the foregoing thin-film deposition techniques incombination with physical masking or photolithographic techniques, areactant component can be delivered to all of the predefined regions onthe substrate in a uniform distribution (i.e., in the stoichiometry ateach predefined region) or, alternatively, in a gradient ofstoichiometries. Moreover, multiple reactant components can be deliveredto all of the predefined regions on the substrate in a gradient ofstoichiometries. For example, a first component can be deposited througha 100-hole mask from left to right as a gradient layer ranging fromabout 100 Å to about 1,000 Å in thickness. Thereafter, a secondcomponent can be deposited through a 100-hole mask from top to bottom asa gradient layer ranging from about 200 Å to about 2,000 Å in thickness.Once the components have been delivered to the substrate, the substratewill contain 100 predefined regions with varying ratios of the twocomponents in each of the predefined regions. In addition, using theforegoing thin-film deposition techniques in combination with physicalmasking techniques, a reactant component can be delivered to aparticular predefined region on the substrate in a uniform distributionor, alternatively, in a gradient of stoichiometries.

[0103] It will be readily apparent to those of skill in the art that theforegoing deposition techniques are intended to illustrate, and notrestrict, the ways in which the reactants can be deposited on thesubstrate in the form of thin-films. Other deposition techniques knownto and used by those of skill in the art can also be used.

[0104]FIG. 2 and FIG. 3 illustrate the use of the physical maskingtechniques which can be used in conjunctions with the aforementionedthin-film deposition techniques. More particularly, FIG. 2 illustratesone embodiment of the invention disclosed herein in which a substrate 2is shown in cross-section. The mask 8 can be any of a wide variety ofdifferent materials including, for example, polymers, plastics, resins,silicon, metals, inorganic glasses, etc. Other suitable mask materialswill be readily apparent to those of skill in the art. The mask isbrought into close proximity with, imaged on, or brought directly intocontact with the substrate surface as shown in FIG. 2. “Openings” in themask correspond to regions on the substrate where it is desired todeliver a reactant. Conventional binary masking techniques in whichone-half of the mask is exposed at a given time are illustratedhereinbelow. It will be readily apparent to those of skill in the art,however, that masking techniques other than conventional binary maskingtechniques can be used in the methods of the present invention.

[0105] As shown in FIG. 3A, the substrate 2 is provided with regions 22,24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50 and 52. Regions38, 40, 42, 44, 46, 48, 50 and 52 are masked, as shown in FIG. 3B, andcomponent A is delivered to the exposed regions in the form of athin-film using, for example, spraying or sputtering techniques, withthe resulting structure shown in FIG. 3C. Thereafter, the mask isrepositioned so that regions 26, 28, 34, 36, 42, 44, 50 and 52 aremasked, as shown in FIG. 3D, and component B is delivered to the exposedregions in the form of a thin-film, with the resulting structure shownin FIG. 3E.

[0106] As an alternative to repositioning the first mask, a second maskcan be used and, in fact, multiple masks are frequently required togenerate the desired array of reactants. If multiple masking steps areused, alignment of the masks may be performed using conventionalalignment techniques in which alignment marks (not shown) are used toaccurately overly successive masks with previous patterning steps, ormore sophisticated techniques can be used. Moreover, it may be desirableto provide separation between exposed areas to account for alignmenttolerances and to ensure separation of reaction sites so as to preventcross-continuation. In addition, it will be understood by those of skillin the art that the delivery techniques used to deliver the variousreactants to the regions of interest can be varied from reactant toreactant, but, in most instances, it will be most practical to use thesame deposition technique for each of the reactants.

[0107] After component B has been delivered to the substrate, regions30, 32, 34, 36, 46, 48, 50 and 52 are masked, as shown in FIG. 3F, usinga mask different from that used in the delivery of components A and B.Component C is delivered to the exposed regions in the form of athin-film, with the resulting structure shown in FIG. 3G. Thereafter,regions 24, 28, 32, 36, 40, 44, 48 and 52 are masked, as shown in FIG.3H, and component D is delivered to the exposed regions in the form of athin-film, with the resulting structure shown in FIG. 3I. Once thecomponents of interest have been delivered to appropriate predefinedregions on the substrate, they are simultaneously reacted using any of anumber of different synthetic routes to form an array of at least twomaterials.

[0108] As previously mentioned, masking techniques other thanconventional binary masking techniques can be employed with theaforementioned thin-film deposition techniques in the methods of thepresent invention. For example, FIG. 4 illustrates a masking techniquewhich can be employed to generate an array of materials, each consistingof a combination of three different components, formed from a base groupof four different components. In non-conventional binary techniques, aseparate mask is employed for each of the different components. Thus, inthis example, four different masks are employed. As shown in FIG. 4A,the substrate 2 is provided with regions 54, 56, 58 and 60. Region 56 ismasked, as shown in FIG. 4B, and component A is delivered to the exposedregions in the form of a thin-film using, for example, spraying orsputtering techniques, with the resulting structure shown in FIG. 4C.Thereafter, a second mask is employed to mask region 54, as shown inFIG. 4D, and component B is delivered to the exposed regions in the formof a thin-film, with the resulting structure shown in FIG. 4E.Thereafter, region 58 is masked using a third mask, as shown in FIG. 4F,and component C is delivered to the exposed regions in the form of athin-film, with the resulting structure shown in FIG. 4G. Finally, afourth mask is employed to mask region 60, as shown in FIG. 4H, andcomponent D is delivered to the exposed regions in the form of athin-film, with the resulting structure shown in FIG. 4I. Once thecomponents of interest have been delivered to appropriate predefinedregions on the substrate, they are simultaneously reacted using any of anumber of different synthetic routes to form an array of four differentmaterials.

[0109]FIG. 5 illustrates another masking technique which can be employedto generate an array of materials, each consisting of a combination ofthree different components, formed from a base group of six differentcomponents. As shown in FIG. 5A, the substrate 2 is provided withregions 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92,94, 96, 98 and 100. Regions 64, 68, 72, 76, 80, 84, 88, 92, 96 and 100are masked, as shown in FIG. 5B, and component A is delivered to theexposed regions in the form of a thin-film using, for example, sprayingor sputtering techniques, with the resulting structure shown in FIG. 5C.Thereafter, a second mask is employed to mask regions 62, 66, 72, 74,80, 82, 88, 90, 96 and 98, as shown in FIG. 5D, and component B isdelivered to the exposed regions in the form of a thin-film, with theresulting structure shown in FIG. 5E. Thereafter, regions 64, 66, 70,74, 78, 82, 86, 92, 96, and 100 are masked using a third mask, as shownin FIG. 5F, and component C is delivered to the exposed regions in theform of a thin-film, with the resulting structure shown in FIG. 5G.Thereafter, a fourth mask is employed to mask regions 64, 66, 70, 76,78, 84, 88, 90, 94 and 98, as shown in FIG. 5H, and component D isdelivered to the exposed regions in the form of a thin-film, with theresulting structure shown in FIG. 5L Thereafter, regions 62, 68, 70, 74,80, 84, 86, 90, 94 and 100 are masked with a fifth mask, as shown inFIG. 5J, and component E is delivered to the exposed regions in the formof a thin-film, with the resulting structure shown in FIG. 5K. Finally,a sixth mask is employed to mask regions 62, 68, 72, 76, 78, 82, 86, 92,94 and 98, as shown in FIG. 5L, and component F is delivered to theexposed regions in the form of a thin-film, with the resulting structureshown in FIG. 5M. Once the components of interest have been delivered toappropriate predefined regions on the substrate, they are simultaneouslyreacted using any of a number of different synthetic routes to form anarray of 20 different materials.

[0110] It will be readily apparent to those of skill in the art thatalternative masking techniques can be employed to generate an array ofmaterials, each consisting of a combination of 3 or more components,formed from a base group of four or more components.

[0111] B. Delivery Using A Dispenser

[0112] In addition to the foregoing delivery techniques, dispensers canbe utilized to generate diverse combinations of reactant components inthe form of droplets or powder on a single substrate. As explainedabove, commercially available micropipetting apparatus can be adapted todispense droplet volumes of 5 nanoliters or smaller from a capillary.Such droplets can fit within a reaction region having a diameter of 300μm or less when a non-wetting mask is employed. In some embodiments, themicropipette is accurately and precisely positioned above the reaction,as described below, before the reactant solution is deposited.

[0113] In a different preferred embodiment, the present inventionemploys a solution depositing apparatus that resembles devices commonlyemployed in the inkjet printing field. Such inkjet dispensers include,for example, the pulse pressure type, the bubble jet type and the slitjet type. In an ink-jet dispenser of the pulse pressure type, theprinting ink is jetted from a nozzle according to a change in pressureapplied by a piezoelectric device. In an ink-jet dispenser of the bubblejet type, bubbles are generated with heat generated with a resistancedevice embedded in a nozzle, and printing ink is jetted by using theforce due to the expansion of a bubble. In an ink-jet dispenser of theslit jet type, printing ink is filled within a slit-like orifice whereinrecording electrodes are aligned in correspondence to pixels, and a DCvoltage pulse is applied between a recording electrode and a counterelectrode arranged behind a recording paper. In this system, theprinting ink around the top of the record electrode is chargedelectrically so that the ink is ejected towards the recording paper withan electrostatic force to record a dot on the paper.

[0114] Such ink-jet printers can be used with minor modification bysimply substituting a reactant containing solution or reactantcontaining powder for the ink. For example, Wong, et al., EuropeanPatent Application 260 965, incorporated herein by reference for allpurposes, describes the use of a pulse pressure type inkjet printer toapply an antibody to a solid matrix. In the process, a solutioncontaining the antibody is forced through a small bore nozzle that isvibrating in a manner that fragments the solution into discretedroplets. The droplets are subsequently charged by passing through anelectric field and then deflected onto the matrix material.

[0115] For illustrative purposes, a conventional ink drop printer of thepulse pressure type includes a reservoir in which ink is held underpressure. The ink reservoir feeds a pipe which is connected to a nozzle.An electromechanical transducer is employed to vibrate the nozzle atsome suitable high frequency. The actual structure of the nozzle mayhave a number of different constructions, including a drawn glass tubewhich is vibrated by an external transducer, or a metal tube vibrated byan external transducer (e.g., a piezoelectric crystal), or amagnetostrictive metal tube which is magnetostrictively vibrated. Theink accordingly is ejected from the nozzle in a stream which shortlythereafter breaks into individual drops. An electrode may be presentnear the nozzle to impart a charge to the droplets.

[0116] A schematic drawing of an ink drop dispenser of the pulsepressure type (such as is described in U.S. Pat. Nos. 3,281,860 and4,121,222, which are incorporated by reference herein for all purposes)which may be employed in the present invention is shown in FIG. 6. Thisapparatus comprises a reservoir 210 which contains a solution underpressure. Tubing 212 is connected to the reservoir 210 and terminates ina metal nozzle 242. Nozzle 242 is disposed within a hole provided inpiezoelectric crystal 240. The end of the metal tube and of thepiezoelectric crystal are made to coincide. The tubing and thepiezoelectric crystal are soldered together to form a permanentwaterproof attachment. The coincident ends of the crystal and the tubingare covered with a washer 244 which is termed an orifice washer. Thiswasher has an opening 246 drilled therethrough through which thesolution is emitted under pressure. A source of oscillations 218 isconnected between the outside of the metal tubing 242 and the outside ofthe piezoelectric crystal 240. The construction is such that hermeticsealing can be employed which protects against electrochemical andatmospheric attack of the components.

[0117] The piezoelectric crystal 240 is vibrated substantially at thefrequency of the source of oscillations causing the tubing and nozzle tovibrate whereby the solution stream breaks down into droplets 246. Asignal source 224 which is synchronized by the source of oscillations isconnected between the nozzle and the charging cylinder 226. As a result,each of the drops, which should be substantially the same mass, receivesa charge, the amplitude of which is determined by the amplitude of thesignal applied from the source 224 and the charging cylinder 226.

[0118] The charged drops, after passing through the charging cylinder,pass into an electric field which is established between two platesrespectively 230 and 232 which are connected to a field potential source234. As a result of the action between the field and the charge of eachdrop, the drops are deflected from their center line path between theplates in accordance with the charge which they carry. Thus, when theyfall on an optionally moving writing medium 236, a deposition patternoccurs on the writing medium representative of the information in thesignals.

[0119] Although the inkjet printer of the pulse pressure type has beendescribed in greater detail herein for purposes of illustration, it willbe readily apparent to those of skill in the art that inkjet printers ofthe bubble jet type and the slit jet type can also be used, with onlyminor modifications, to deliver reactant components to predefinedregions on the substrate. Moreover, although the foregoing discussionrefers to a single nozzle, it will be readily apparent to those of skillin the art that ink-jet printers having multiple nozzles can be used todeliver multiple reactant components to a single predefined region onthe substrate or, alternatively, to multiple predefined regions on thesubstrate. In addition, as improvements are made in field of ink-jetprinters, such improvements can be used in the methods of the presentinvention.

[0120] In other embodiments, the reactant solutions can be deliveredfrom a reservoir to the substrate by an electrophoretic pump. In such adevice, a thin capillary connects a reservoir of the reactant with thenozzle of the dispenser. At both ends of the capillary, electrodes arepresent to provide a potential difference. As is known in the art, thespeed at which a chemical species travels in a potential gradient of anelectrophoretic medium is governed by a variety of physical properties,including the charge density, size, and shape of the species beingtransported, as well as the physical and chemical properties of thetransport medium itself. Under the proper conditions of potentialgradient, capillary dimensions, and transport medium rheology, ahydrodynamic flow will be set up within the capillary. Thus, bulk fluidcontaining the reactant of interest can be pumped from a reservoir tothe substrate. By adjusting the appropriate position of the substratewith respect to the electrophoretic pump nozzle, the reactant solutioncan be precisely delivered to predefined reaction regions.

[0121] Using the aforementioned dispenser systems, the reactants can bedelivered to predefined regions on the substrate either sequentially orsimultaneously. In a presently preferred embodiment, the reactants aresimultaneously delivered to either a single predefined region on thesubstrate or, alternatively, to multiple predefined regions on thesubstrate. For example, using an ink-jet dispenser having two nozzles,two different reactants can be simultaneously delivered to a singlepredefined region on the substrate. Alternatively, using this sameinkjet dispenser, a reactant can be simultaneously delivered to twodifferent predefined regions on the substrate. In this instance, thesame reactant or, alternatively, two different reactants can bedelivered. If the same reactant is delivered to both of the predefinedregions, it can be delivered at either the same or differentconcentrations. Similarly, using an ink-jet dispenser having eightnozzles, for example, eight different reactants can be simultaneouslydelivered to a single predefined region on the substrate or,alternatively, eight reactants (either the same or different) can besimultaneously delivered to eight different predefined regions on thesubstrate.

[0122] V. Moving the Dispenser with Respect to the Substrate

[0123] To deposit reactant droplets consistently at precisely specifiedregions using a dispenser, a frame of reference common to the deliveryinstrument and the substrate is required. In other words, the referencecoordinates of the instrument must be accurately mapped onto thereference coordinates of the substrate. Ideally, only two referencepoints on the substrate would be required to completely map the array ofreaction regions. The dispenser instrument locates these referencepoints and then adjust its internal reference coordinates to provide thenecessary mapping. After this, the dispenser can move a particulardistance in a particular direction and be positioned directly over aknown region. Of course, the dispenser instrument must provide preciselyrepeatable movements. Further, the individual regions of the array mustnot move with respect to the reference marks on the substrate after thereference marks have been formed. Unfortunately, pressing or othermechanical operations commonly encountered during fabrication and use ofa substrate can warp the substrate such that the correspondence betweenthe reference marks and the reaction regions is altered.

[0124] To allow for this possibility, a substrate containing both“global” and “local” reference marks is employed. In preferredembodiments, only two global reference marks are conveniently located onthe substrate to define the initial frame of reference. When thesepoints are located, the dispenser instrument has an approximate map ofthe substrate and the predefined regions therein. To assist in locatingthe exact position of the regions, the substrate is further subdividedinto local frames of reference. Thus, in an initial, “course”adjustment, the dispenser is positioned within one of the local framesof reference. Once in the local region, the dispensing instrument looksfor local reference marks to define further a local frame of reference.From these, the dispenser moves exactly to the reaction region where thereactant is deposited. In this manner, the effects of warpage or otherdeformation can be minimized. The number of local reference marks isdetermined by the amount of deformation expected in the substrate. Ifthe substrate is sufficiently rigid so that little or no deformationwill occur, very few local reference marks are required. If substantialdeformation is expected, however, more local reference marks arerequired.

[0125] Starting at a single reference point, the micropipette or otherdispenser is translated from one reaction region to other reactionregions of the substrate by a correct distance in the correct direction(this is the “dead reckoning” navigational technique). Thus, thedispenser can move from region to region, dispensing correctly meteredamounts of reactant. In order to initially locate the reference pointand align the dispenser directly over it, a vision or blind system canbe employed. In a vision system, a camera is rigidly mounted to thedispenser nozzle. When the camera locates the reference point(s), thedispenser is known to be a fixed distance and direction away from thepoint, and a frame of reference is established. Blind systems locate thereference point(s) by capacitive, resistive, or optical techniques, forexample. In one example of an optical technique, a laser beam istransmitted through or reflected from the substrate. When the beamencounters a reference mark, a change in light intensity is detected bya sensor. Capacitive and resistive techniques are similarly applied. Asensor registers a change in capacitance or resistivity when a referencepoint is encountered.

[0126] For purposes of this invention, the spacing between theindividual regions will vary in accordance with the size of the regionsused. For example, if a 1 mm² region is used, the spacing between theindividual regions will preferably be on the order of 1 mm or less. If,for example, a 10 μm² region is used, the spacing between the individualregions will preferably be on the order of 10 μm or less. Further, theangular relation between the cells is preferably consistent, to within0.1 degrees. Of course, the photolithographic or other process used todefine the arrangement of cells will accurately define the angle andspacing. However, in subsequent processes (e.g., pressing processes),the angle can be distorted. Thus, in some embodiments, it may benecessary to employ “local” reference points throughout the array.

[0127] Translational mechanisms capable of moving with the desiredprecision are preferably equipped with position feedback mechanisms(i.e., encoders) of the type used in devices for semiconductor devicemanufacturing and testing. Such mechanisms will preferably be closedloop systems with insignificant backlash and hysteresis. In preferredembodiments, the translation mechanism will have a high resolution,i.e., greater than five motor ticks per encoder count. Further, theelectro-mechanical mechanism will preferably have a high repeatabilityrelative to the region diameter travel distance (preferably, ±1-5 μm).

[0128] To deposit a drop of reactant solution on the substrateaccurately, the dispenser nozzle must be placed a correct distance abovethe surface. The dispenser tip preferably will be located about 0.1 cmto about 3 cm above the substrate surface when the drop is released. Thedegree of control necessary to achieve such accuracy can be attainedwith a repeatable high-resolution translation mechanism of the typedescribed above. In one embodiment, the height above the substrate isdetermined by moving the dispenser toward the substrate in smallincrements, until the dispenser tip touches the substrate. At thispoint, the dispenser is moved away from the surface a fixed number ofincrements which corresponds to a specific distance. From there, thedrop is released to the cell below. Preferably, the increments in whichthe dispenser moves will vary in accordance with the size of the regionsused.

[0129] In an alternative embodiment, the dispenser nozzle is encircledby a sheath that rigidly extends a fixed distance beyond the dispensertip. Preferably, this distance corresponds to the distance at which thesolution drop will fall when delivered to the selected reaction region.Thus, when the sheath contacts the substrate surface, the movement ofthe dispenser is halted and the drop is released. It is not necessary inthis embodiment to move the dispenser back, away from the substrate,after contact is made. In this embodiment, as well as the previousembodiment, the point of contact with the surface can be determined by avariety of techniques such as by monitoring the capacitance orresistance between the tip of the dispenser (or sheath) and thesubstrate below. A rapid change in either of these properties isobserved upon contact with the surface.

[0130] To this point, the dispenser delivery system has been describedonly in terms of translational movements. However, other systems mayalso be employed. In one embodiment, the dispenser is aligned withrespect to the region of interest by a system analogous to that employedin magnetic and optical storage media fields. For example, the region inwhich reactant is to be deposited is identified by a track and sectorlocation on the disk. The dispenser is then moved to the appropriatetrack while the disk substrate rotates. When the appropriate cell ispositioned below the dispenser (as referenced by the appropriate sectoron the track), a droplet of reactant solution is released.

[0131] Control of the droplet size may be accomplished by varioustechniques. For example, in one embodiment, a conventionalmicropipetting instrument is adapted to dispense droplets of fivenanoliters or smaller from a capillary. Such droplets fit within regionshaving diameters of 300 μm or less when a non-wetting mask is employed.

[0132] Although the above embodiments have been directed to systemsemploying liquid droplets, minuscule aliquots of each test substance canalso be delivered to the reaction region as powders or miniaturepellets. Pellets can be formed, for example, from the compound ofinterest and one or more kinds of inert binding material. Thecomposition of such binders and methods for the preparation of the“pellets” will be apparent to those of skill in the art. Such“mini-pellets” will be compatible with a wide variety of testsubstances, stable for long periods of time and suitable for easywithdrawal from the storage vessel and dispensing.

[0133] VI. Synthetic Routes for Reacting the Array of Components

[0134] Once the array of components have been delivered to predefinedregions on the substrate, they can be simultaneously reacted using anumber of different synthetic routes. The components can be reactedusing, for example, solution based synthesis techniques, photochemicaltechniques, polymerization techniques, template directed synthesistechniques, epitaxial growth techniques, by the sol-gel process, bythermal, infrared or microwave heating, by calcination, sintering orannealing, by hydrothermal methods, by flux methods, by crystallizationthrough vaporization of solvent, etc. Other useful synthesis techniqueswill be apparent to those of skill in the art upon review of thisdisclosure. Moreover, the most appropriate synthetic route will dependon the class of materials to be synthesized, and the selection in anygiven case will be readily apparent to those of skill in the art. Inaddition, it will be readily apparent to those of skill in the art that,if necessary, the reactant components can be mixed using, for example,ultrasonic techniques, mechanical techniques, etc. Such techniques canbe applied directly to a given predefined region on the substrate or,alternatively, to all of the predefined regions on the substrate in asimultaneous fashion (e.g., the substrate can be mechanically moved in amanner such that the components are effectively mixed).

[0135] Traditional routes to solid-state synthesis involve the sinteringof solid reactants. The standard method used to synthesizesuperconductors, for example, is to grind several metal-oxide powderstogether, compress the mixture and, thereafter, bake at a temperatureranging from 800° C. to about 1000° C. The elements in the powdermixture sinter, i.e., they react chemically to form new compounds andfuse into a solid, without passing through the liquid or gaseous phase.Gaseous elements, such as oxygen, can be taken up during sintering or,alternatively, in a subsequent step, and the pressure of the system canbe varied during the synthesis process. Unfortunately, using traditionalsintering techniques, reaction rates are limited by the slow diffusionof atoms or ions through solid reactants, intermediates and products.Moreover, high temperatures are frequently required to acceleratediffusion and to thermodynamically drive the formation of a stablephase.

[0136] In contrast to such traditional routes, in the present invention,new routes to solid-synthesis focus on the synthesis of compounds atlower temperatures. It has been found that reaction rates can beincreased at lower temperatures by drastically shortening the distancerequired for diffusion of the reactants and by increasing the surface tovolume ratio. This can be achieved by depositing the reactants on thesubstrate in the form of very thin-films or, alternatively, by usingsolution based synthesis techniques wherein the reactants are deliveredto the substrate in the form of a solution. Moreover, when the synthesisreaction is to be carried out at a temperature ranging from about 200°C. to about 600° C., a molten salt can be employed to dissolve thereactant components. This technique is generally referred to as the fluxmethod. Similarly, in a hydrothermal method, water or other polarsolvent containing a soluble inorganic salt is employed to dissolve thereactant components. The hydrothermal method is usually carried outunder pressure and at a temperature ranging from about 100° C. to about400° C. Moreover, using the various synthetic routes of the presentinvention, the array of reactant components can be pressurized ordepressurized under an inert atmosphere, oxygen or other gas. Inaddition, in the synthetic routes of the present invention, variousregions on the substrate can be exposed to different heat historiesusing, for example, laser thermolysis, wherein bursts of energy of apredetermined duration and intensity are delivered to target regions onthe substrate.

[0137] Furthermore, using the synthetic routes of the present invention,the array of components can be processed between the various deliverysteps. For example, component A can be delivered to a first region on asubstrate and, thereafter, exposed to oxygen at elevated temperature,for example. Subsequently, component B can be delivered to the firstregion on the substrate and, thereafter, components A and B are reactedunder a set of reaction conditions. Other manipulations and processingsteps which can be carried out between the various delivery steps willbe apparent to those of skill in the art upon reading this disclosure.

[0138] As such, using the methods of the present invention, thefollowing materials can be prepared: covalent network solids, ionicsolids and molecular solids. More particularly, the methods of thepresent invention can be used to prepare, for example, inorganicmaterials, intermetallic materials, metal alloys, ceramic materials,organic materials, organometallic materials, non-biological organicpolymers, composite materials (e.g., inorganic composites, organiccomposites, or combinations thereof), etc. High-temperaturesuperconductors can be prepared, for instance, by delivering reactantcomponents to predefined regions on the substrate using, for example,solution based delivery techniques. Once the reactant components ofinterest have been delivered to the substrate, the substrate is heatedto the boiling point of the solvent to evaporate off the solvent.Alternatively, the solvent can be removed by delivering the reactantcomponents to a heated substrate. The substrate is then oxidized toremove unwanted components (e.g., carbon, nitrogen, etc.) from thearray. The substrate is then flash heated at a temperature of about 800°C. to about 875° C. for about two minutes. Thereafter, the reaction israpidly quenched and the array is scanned for materials that aresuperconducting. Magnetic materials can be prepared using a similarprocess except that in the case of magnetic materials, the componentsare delivered to the substrate and simultaneously reacted thereon in thepresence of a magnetic field.

[0139] Moreover, an array of zeolites, i.e., hydrated silicates ofaluminum and either sodium, calcium or both, can be prepared using themethods of the present invention. To prepare an array of such materials,the reactant components are delivered to predefined regions on asubstrate in the form of a slurry. Using a low temperature (e.g., 60° C.to about 70° C.) hydrothermal method, for example, the zeolites willcrystallize out of solution. In addition, organic polymers can beprepared by delivering a monomer (or monomers) of interest to predefinedregions on the substrate usually in the form of a solution. Once themonomer of interest has been delivered, an initiator is added to eachregion on the substrate. The polymerization reaction is allowed toproceed until the initiator is used up, or until the reaction isterminated in some other manner. Upon completion of the polymerizationreaction, the solvent can be removed by, for example, evaporation invacuo.

[0140] It will be readily apparent to those of skill in the art that theforegoing synthetic routes are intended to illustrate, and not restrict,the ways in which the reactants can be simultaneously reacted to form atleast two materials on a single substrate. Other synthetic routes andother modifications known to and used by those of skill in the art canalso be used.

[0141] VII. Methods for Screening the Array of Materials

[0142] Once prepared, the array of materials can be screened in parallelfor materials having useful properties. Either the entire array or,alternatively, a section thereof (e.g., a row of predefined regions) canbe screened in parallel for materials having useful properties. Scanningdetection systems are preferably utilized to screen an array ofmaterials wherein the density of regions per unit area will be greaterthan 0.04 regions/cm², more preferably greater than 0.1 regions/cm²,even more preferably greater than 1 region/cm², even more preferablygreater than 10 regions/cm, and still more preferably greater than 100regions/cm². In most preferred embodiments, scanning detection systemsare preferably utilized to screen an array of materials wherein thedensity of regions per unit area will be greater than 1,000 regions/cm,more preferably 10,000 regions/cm², even more preferably greater than100,000 regions/cm², and still more preferably 10,000,000 regions/cm².

[0143] Accordingly, in a preferred embodiment, the array of materials issynthesized on a single substrate. By synthesizing the array ofmaterials on a single substrate, screening the array for materialshaving useful properties is more easily carried out. Properties whichcan be screened for include, for example, electrical, thermalmechanical, morphological, optical, magnetic, chemical, etc. Moreparticularly, useful properties which can be screened for are set forthin Table I, infra. Any material found to possess a useful property cansubsequently be prepared on a large-scale.

[0144] The properties listed in Table I can be screened for usingconventional methods and devices known to and used by those of skill inthe art. Scanning systems which can be used to screen for the propertiesset forth in Table I include, but are not limited to, the following:scanning Raman spectroscopy; scanning NMR spectroscopy; scanning probespectroscopy including, for example, surface potentialometry, tunnellingcurrent, atomic force, acoustic microscopy, shearing-stress microscopy,ultra fast photo excitation, electrostatic force microscope, tunnelinginduced photo emission microscope, magnetic force microscope, microwavefield-induced surface harmonic generation microscope, nonlinearalternating-current tunnelling microscopy, near-field scanning opticalmicroscopy, inelastic electron tunneling spectrometer, etc.; opticalmicroscopy in different wavelength; scanning optical ellipsometry (formeasuring dielectric constant and multilayer film thickness); scanningEddy-current microscope; electron (diffraction) microscope, etc.

[0145] More particularly, to screen for conductivity and/orsuperconductivity, one of the following devices can be used: a ScanningRF Susceptibility Probe, a Scanning RF/Microwave Split-Ring ResonatorDetector, or a Scanning Superconductors Quantum Interference Device(SQUID) Detection System. To screen for hardness, a nanoindentor(diamond tip) can, for example, be used. To screen formagnetoresistance, a Scanning RF/Microwave Split-Ring Resonator Detectoror a SQUID Detection System can be used. To screen for crystallinity,infrared or Raman spectroscopy can be used. To screen for magneticstrength and coercivity, a Scanning RF Susceptibility Probe, a ScanningRF/Microwave Split-Ring Resonator Detector, a SQUID Detection System ora Hall probe can be used. To screen for fluorescence, a photodetectorcan be used. Other scanning systems known to those of skill in the artcan also be used. TABLE I EXAMPLES OF PROPERTIES WHICH CAN BE SCREENEDFOR ELECTRICAL: SUPERCONDUCTIVTIY CRITICAL CURRENT CRITICAL MAGNETICFIELD CONTDUCTIVITY RESISTIVITY FOR RESISTIVE FILMS DIELECTRIC CONSTANTDIELECTRIC STRENGTH DIELECTRIC LOSS STABILIIY UNDER BIAS POLARIZATIONPERMITTIVITY PIEZOELECTRICITY ELECTROMIGRATION THERMAL: COEFFICIENT OFEXPANSION THERMAL CONDUCTIVITY TEMPERATURE VARIATION VOLATILITY & VAPORPRESSURE MECHANICAL: STRESS ANISOTROPY ADHESION HARDNESS DENSITYDUCTILITY ELASTICITY POROSITY MORPHOLOGY: CRYSTALLINE OR AMORPHOUSMICROSTRUCTURE SURFACE TOPOGRAPHY CRYSTALLITE ORIENTATION OPTICAL:REFRACTIVE INDEX ABSORPTION BIREFRINGENCE SPECTRAL CHARACTERISTICSDISPERSION FREQUENCY MODULATION EMISSION MAGNETIC: SATURATION FLUXDENSITY MAGNETORESISTANCE MAGNETORESTRICTION COERCIVE FORCE MAGNETIC:PERMEABILITY CHEMICAL: COMPOSITION COMPLEXATION ACIDITY-BASICITYCATALYSIS IMPURITIES REACTIVITY WITH SUBSTRATE CORROSION & EROSIONRESISTANCE

[0146] The arrays of the present invention can be screened sequentiallyor, alternatively, they can be screened in parallel using a scanningsystem. For instance, the array of materials can be sequentiallyscreened for superconductivity using, for example, magnetic decoration(Bitter pattern) and electron holography. Alternatively, the array ofmaterials can be scanned for superconductivity using, for example, aHall-probe, magnetic force microscopy, SQUID microscopy, a ACsusceptibility microscope, a microwave absorption microscope, an Eddycurrent microscope, etc.

[0147] In a presently preferred embodiment, a scanning detection systemis employed. In one embodiment, the substrate having an array ofmaterials thereon is fixed and the detector has X-Y motion. In thisembodiment, the substrate is placed inside a sealed chamber, close tothe detector. The detector (e.g., an RF Resonator, a SQUID detector,etc.) is attached to a rigid rod with low thermal conductivity coupledto an X-y positioning table at room temperature with a scanning range ofup to 1 inch and a 2 μm spatial resolution. The position of the detectoris controlled using stepping motors (or servomotors) connected to acomputer-controlled positioner. The temperature of the detector and thesubstrate can be lowered via helium exchange gas by liquid heliumreservoir located around the chamber. This scanning system can beoperated at temperatures ranging from 600° K down to 4.2° K (whenimmersed in liquid helium).

[0148] In another embodiment, the detector is fixed and the substratehaving an array of materials thereon has R-θ motion. In this embodiment,the substrate is placed on a rotating stage (e.g., a spur gear) drivenby a gear rack which is coupled to a micrometer and a stepping motor.This rotating stage is located on a cryogenic sliding table which isdriven by a separate micrometer and stepping motor system. This systemis capable of scanning an area having a 1 inch radius with a 1 μmspatial resolution. The scanning and probing are controlled through theuse of a computer. As with the other embodiment, the temperature of thedetector and the substrate can be lowered via helium exchange gas usinga liquid helium reservoir located around the chamber. This scanningsystem can be operated at temperatures ranging from 600° K down to 4.2°K (when immersed in liquid helium).

[0149] Using either of the foregoing embodiments, a Scanning RFSusceptibility Detection System can, for example, be used to detect thesuperconductivity of a large array of materials (see, e.g., FIG. 7).Using photolithographic techniques, a micro (about 1×1 mm²) spiral coilcan be fabricated to probe the conductivity of a sample adjacent to thecoil. The signals are picked up by a phase-sensitive detectionelectronic circuit. Thereafter, the data is analyzed by a computer toobtain a correlation between the properties and stoichiometry of a givensample. If desired, analytical results can be fed back to the deliverysystem so that the system can “zoom in” on the most promisingstoichiometry in the next synthesis cycle.

[0150] Moreover, a superconducting microcircuit implementation of aparallel LC resonance circuit can be used to scan the array of materialsfor those that are superconducting. A parallel LC circuit is simply aninductor in parallel with a capacitor. The electrical properties of bothcircuit elements give the circuit a resonance frequency where a maximumamount of input voltage is transmitted through to the output. Thesharpness of the peak, conventionally measured by its Q value, isdetermined by the materials used in the circuit, whereas the frequencyof the resonance is set by the capacitance and the inductance. It hasbeen determined that manufacturing the circuit out of a superconductingmaterial, such as niobium, gives a very high Q value, i e., a Q value onthe order of 10,000 or more. This is in contrast to commerciallyavailable, non-superconducting capacitors and inductors which generallygive Q values on the order of hundreds. The steep peak of the niobiumcircuit gives rise to high sensitive detection.

[0151] In this system, actual detection is done by the induction coil.The inductance of an inductor is a function of the magnetic fieldgeometry through its coils. In the presence of a nearby superconductingsample, the magnetic field through the inductor is distorted by theexpulsion of field by the material (i.e., the Meissner effect). This, inturn, changes the inductance and shifts the resonance. By following theresonance, one can readily determine when a material is superconducting.

[0152] In this scanning device, the total circuit is approximately 5mm×2.5 mm, with an active area equal to approximately one-fourth ofthat. The coil is a spiral coil having dimensions of about 1.5 mm perside, and the capacitor is a two-plate niobium capacitor with a SiO₂dielectric (i.e., insulating) layer SQUID magnetometers have achievedspatial resolutions of 10 μm, but their sensitivities have been limitedby noise present in the Josephson junction. In the scanning device ofthe present invention, however, the device is unencumbered by noise fromthe Josephson junction and, thus, a sensitivity for samples of 1 μm orless can be achieved. In this embodiment, sensitivity, rather thanspatial resolution, is a more critical criterion.

[0153] It will be readily apparent to those of skill in the art that theforegoing detection systems are intended to illustrate, and notrestrict, the ways in which the array of material can be screened forthose materials having useful properties. Other detection systems knownto and used by those of skill in the art can similarly be used.

[0154] VIII. Alternative Embodiments

[0155] In another embodiment of the present invention, at least twodifferent arrays of materials are prepared by delivering substantiallythe same reaction components at substantially identical concentrationsto predefined regions on both first and second substrates and,thereafter, subjecting the components on the first substrate to a firstset of reaction conditions and the components on the second substrate toa second set of reaction conditions in a wide array of compositions. Ifa first substrate has, for example, components A and B on a first regionon the substrate and, in addition, components X and Y on a second regionon the substrate, the second substrate is prepared in a manner such thatit has substantially the same components in predefined regions. That isto say, the second substrate is substantially identical to the firstsubstrate in terms of the components contained thereon. As such, in thisexample, the second substrate would also have components A and B on thefirst region of the substrate and, in addition, components X and Y onthe second region on the substrate.

[0156] Once the components have been delivered to their appropriatepredefined regions on the substrate, the components on the firstsubstrate are reacted using a first set of reaction conditions, whereasthe components on the second substrate are reacted using a second set ofreaction conditions. It will be understood by those of skill in the artthat the components on the first substrate can be reacted under a firstset of reaction conditions at the same time as the components on thesecond substrate are reacted under a second set of reaction conditionsor, alternatively, the components on the first substrate can be reactedunder a first set of reaction conditions either before or after thecomponents on the second substrate are reacted under a second set ofreaction conditions.

[0157] In this embodiment, the effects of various reaction parameterscan be studied and, in turn, optimized. Reaction parameters which can bevaried include, for example, reactant amounts, reactant solvents,reaction temperatures, reaction times, the pressures at which thereactions are carried out, the atmospheres in which the reactions areconducted, the rates at which the reactions are quenched, etc. Otherreaction parameters which can be varied will be apparent to those ofskill in the art. Alternatively, the first set of reaction conditionscan be the same as the second set of reaction conditions, but, in thisembodiment, the processing steps after the components on the first andsecond substrates have been reacted would differ from the firstsubstrate to the second substrate. For example, the first substrate canbe exposed to oxygen at elevated temperatures, while the secondsubstrate is not processed at all.

[0158] Alternatively, in another aspect of this embodiment, the firstsubstrate having component A on the first region of the substrate andcomponent X on the second region of the substrate is exposed to aparticular set of reaction conditions (e.g., exposed to oxygen atelevated temperatures), while the second substrate also having componentA on the first region of the substrate and component X on the secondregion of the substrate is not exposed to such reaction conditions.Thereafter, component B is delivered to the first region of both thefirst and second substrates, and component Y is delivered to the secondregion of both the first and second substrates. Once the desiredcomponents have been delivered to the first and second regions on thefirst and second substrates, the components are simultaneously reactedunder substantially identical reaction conditions. This particularembodiment allows one to determine the effects intermediate processingsteps have on a particular array of materials. As set forth above, anyof a number of different reaction parameters can be varied.

[0159] In still another embodiment of the present invention, a method isprovided for producing an array of materials varying from one another interms of chemical composition and component stoichiometries. In thismethod, a reactant component can be delivered to a particular predefinedregion(s) in a gradient of stoichiometries. Moreover, multiple reactantcomponents can be delivered to a particular predefined region(s) in agradient of stoichiometries. For example, a first component of a firstmaterial is deposited in a gradient of stoichiometries from left toright on the first reaction region. Thereafter, a first reactioncomponent of a second material is deposited in a gradient ofstoichiometries from left to right on the second reaction region.Thereafter, a second component of the first material is deposited in agradient of stoichiometries from top to bottom on the first reactionregion. Thereafter, a second component of the second material isdeposited in a gradient of stoichiometries from top to bottom on thesecond reaction region. Once the components have been delivered to thesubstrate, the components are simultaneously reacted to form materialsvarying from one another in terms of chemical composition and chemicalstoichiometries.

[0160] In yet another embodiment of the present invention, a materialhaving a useful property is provided. The material is prepared by aprocess comprising the steps of: (a) forming an array of differentmaterials on a single substrate; (b) screening the array for a materialhaving a useful property; and (c) making additional amounts of thematerial having the useful property. Such materials include, forexample, intermetallic materials, metal alloys, ceramic materials,organometallic materials, organic polymers, composite materials (e.g.,inorganic composites, organic composites, or combinations thereof), etc.In addition, useful properties include, for example, electrical,thermal, mechanical, morphological, optical, magnetic, chemical, etc.

[0161] It will be understood by those of skill in the art that theforegoing discussions directed to the various delivery techniques,synthetic routes, screening methods, etc. are fully applicable to theabove embodiments of the present invention.

IX. EXAMPLES

[0162] The following examples are provided to illustrate the efficacy ofthe inventions herein.

[0163] A. Synthesis of an Array of Copper Oxide Thin-Film Materials

[0164] This example illustrates the synthesis and screening of an arrayof copper oxide thin-film materials. The reactants were delivered to a1.25 cm×1.25 cm MgO substrate with a (100) polished surface. Thesubstrate having 16 predefined regions thereon was contained in areaction chamber in vacuo. The reactants were delivered to the substratein the form of thin-films using a sputtering system in combination withbinary masking techniques. The binary mask was made of stainless steel.A RF magnetron gun sputtering system was used to deliver the reactantcomponents to the predefined regions on the substrate. The RF magnetronsputtering gun (Mini-mak manufactured by US, Inc., Campbell, Calif.)used was about 1.3 inches in diameter. With RF input power (supplied bya Plasmtherm-2000 with a matching network) of 50 to about 200 W,deposition rates ranged from about 0.3 ∪/s to about 2 ∪/s for the fivedifferent reactant components. The RF magnetron sprayer was positionedabout 3 to 4 inches above the substrate and the uniformity of depositedfilm was about 5% over a 1 to 2 inch diameter area. The sputtering gasflow (Ar or Ar and O₂) was controlled by metering valves anddifferential pumping through a manual gate valve. To achieve a highdeposition rate, it was determined that the best gas pressure range wasabout 5 to 15 mTorr. The partial pressure of each gas component in thechamber was monitored using a residual gas analyzer (Micropole Sensor byFerran Scientific, San Diego, Calif.) directly up to 15 mTorr withoutdifferential pumping.

[0165] The reactant components used to generate the array of copperoxide materials were as follows: CuO, Bi₂O₃, CaO, PbO and SrCO₃. CuO wasused as the base element in an effort to discover new copper oxidematerials and, thus, this component was delivered to each of the 16predefined regions on the substrate. Prior to delivering the componentof interest to the predefined regions on the substrate, the base airpressure of the reaction chamber was lowered, within 10 to 15 minutes,to about 10⁻³ to 10⁻⁴ Torr by a 250 l/s turbo pump and, if necessary, itwas furthered lowered to 10⁻⁸ Torr using extended pumping time incombination with heating the reaction chamber to about 100° C. to about150° C. Since only a single RF magnetron gun sputtering system wasemployed, the vacuum was broken and reestablished each time thecomponent was changed. The film deposition thickness was monitored usinga crystal micro-balance (STM-100 by Sycon Instruments, Syracuse, N.Y.).Since the position of crystal micro-balance was not located at exactlythe same position as the substrate, it was necessary to calibrate thethickness monitor reading for each component with a profilometer.

[0166] The reactant components were delivered to the MgO substrate inthe following order: Bi₂O₃, PbO, CuO, CaO and SrCO₃. The stoichiometrywas designed so that each of the five components was present in equalmolar amounts, i.e., 1 Bi:1 Pb:1 Cu:1 Sr:1 Ca as deposited film. Thetotal thickness of the film was about 0.5 μm for a five layered site.The thickness of each of the individual films as well as the sputteringrates at which each of the components were deposited are set forth inTable II, supra. TABLE II DEPOSITION THICKNESS AND SPUTTERING RATE FORTHE COMPONENTS USED TO GENERATE AN ARRAY OF COPPER OXIDES ComponentDeposition Thickness Sputtering Rate Bi₂O₃ 1200 Å  2 Å/Sec PbO 970 Å 1.6Å/Sec   CuO 540 Å 1 Å/Sec SrCO₃ 1650 Å  3 Å/Sec CaO 720 Å 3 Å/Sec

[0167] Once the components of interest were delivered to the 16predefined regions on the substrate as illustrated in FIG. 8, thesubstrate was placed in a furnace, and the components were subsequentlyreacted. FIG. 9 is a photograph of the array of 16 different compoundson the 1.25 cm×1.25 cm MgO substrate. The color of each site is thenatural color of reflected light from a white light source at an angle.The components were simultaneously reacted using the following heatingand cooling procedure: 50° C. to 725° C. in 2 hr., 725° C. to 820° C. in1 hr., 820° C. to 840° C. in 0.5 hr. and 840° C. to 750° C. in 0.5 hr.Once the substrate cooled to a temperature of about 750° C., the powerwas turned off. The heating and cooling procedure was performed inambient atmosphere. No apparent evaporation or melting was observed.

[0168] Once reacted, each of the 16 predefined reaction regions werescreened for resistance. In doing so, it was found that two of thepredefined regions contained materials which are conducting. Contactswere put on these two sites in in-line 4-probe configuration, and it wasdetermined that the contact resistances are less than hundred ohms (i).Thereafter, the samples were cooled down to 4.2° K in a liquid heliumcryostat to measure resistivity as a function of temperature. Factorycalibrated Cemox™ resistance temperature sensor (LakeShore) was used tomeasure temperature. FIGS. 10A and 10B shows the resistance of the twoconducting materials as a function of temperature. The BiPbCuSrCamaterial has a metallic conductivity (resistance decrease withtemperature) from room temperature down to about 100° K, whereas theBiCuSrCa material has a rather flat and slightly upward temperaturedependence resistance. Superconducting critical temperatures (T_(c)) forboth samples are about 100° K. Evidence of two superconducting phases inthe resistivity measurement was not observed.

[0169] B. Synthesis of an Array of 16 Different Organic Polymers

[0170] This example illustrates the possible synthesis of an array of 16different organic polymers formed by the polymerization of styrene withacrylonitrile. A 3 cm×3 cm pyrex substrate having 16 predefined regionsthereon is used in this example. Each of the predefined regions is 3mm×3 mm×5 mm and, thus, the volume of each predefined region is about 45μL. To ensure that the reactants in a given region do not move toadjacent regions, 35 μL reaction volumes will be used.

[0171] A 2 M solution of the styrene monomer in toluene and a 2 Msolution of acrylonitrile in toluene are used. The initiator used toinitiate the polymerization reaction is benzoyl peroxide. A 70 mMsolution of benzoyl peroxide in toluene is used. The initiator ispresent in each of the reactions at a 10 mM concentration. The styrene,acrylonitrile and benzoyl peroxide solutions are delivered to each ofthe 16 predefined regions on the substrate using an ink-jet dispenserhaving three nozzles. The first nozzles is connected to a reservoircontaining the 2 M solution of styrene in toluene, the second nozzle isconnected to a reservoir containing the 2 M solution of acrylonitrile intoluene, and the third nozzle is connected to a reservoir containing the70 mM solution of benzoyl peroxide in toluene. The initiator isdelivered to each of the 16 predefined regions only after the monomershave been delivered.

[0172] To generate an array of 16 different polymers of styrene andacrylonitrile, the reactant amounts set forth in Table II, infra, aredelivered to the 16 predefined regions on the substrate. Once themonomers have been delivered to the 16 predefined regions on thesubstrate, 5 μL of the 70 mM initiator solution is added. Thepolymerization reaction is carried out at a temperature of about 60° C.and at ambient pressure. The reactions are allowed to proceed until theterminator is used up. Upon completion of the polymerization reaction,the organic solvent is removed by evaporation in vacuo (100 Torr). Theresulting polymers can be screened for hardness using, for example, ananoindentor (sharp tip). TABLE III VARIOUS REACTANT COMPONENTS USED TOGENERATE AN ARRAY OF 16 DIFFERENT POLYMERS Amount of 2 M Solution Amountof 2 M Solution Reaction Region of Styrene (μL) of Aczylonitrile (μL) 130 0 2 28.5 1.5 3 27 3 4 25.5 4.5 5 24 6 6 22.5 7.5 7 21 9 8 19.5 10.5 918 12 10  16.5 13.5 11  15 15 12  13.5 16.5 13  12 18 14  10.5 19.5 15 9 21 16  7.5 22.5

[0173] C. Synthesis of an Array of Zeolites

[0174] This example illustrates a possible method for the synthesis ofan array of different zeolites. The reactants are delivered to a 9 cm×9cm Teflon substrate having 16 predefined regions thereon. The substrateis placed in a sealed container having a temperature of about 100° C.Each of the 16 predefined regions on the substrate is a 1 cm×1 cm×2 cmwell. The reactants are delivered to the substrate using a automatedpipette.

[0175] The five components used to generate the array of zeolites are asfollows: Na₂O.Al₂O₃.5H₂O, KOH, Na₂O.2SiO₂.5H₂O, NaOH and H₂O. The firstfour components are dissolved in water to concentrations of 2.22 M, 2.22M, 8.88 M and 11.1 M, respectively. In delivering the components to thepredefined regions on the substrate, it is important that theNa₂O.2SiO₂.5H₂O solution is added last. The five reactant components aredelivered to the predefined regions on the substrate in the amounts setforth in Table III, supra.

[0176] Once the foregoing components have been delivered to theappropriate predefined regions on the substrate and allowed to react,the array can be scanned for microstructure using a Raman LightScattering System. Scanning of the array can begin 2 to 3 hours afterthe components have been delivered to the substrate and can continue foranywhere from 5 to 10 days. In this example, Zeolite A will initially beformed at reaction region 1. With time, however, Zeolite A will beconverted to Zeolite P. Zeolite X will be formed at reaction region 3.Sodalite will be formed at reaction region 6. Zeolite L will be formedat reaction region 12. In addition, other zeolites may be formed atother reaction regions on the substrate. TABLE IV. VARIOUS REACTANTCOMPONENTS USED TO GENERATE AN ARRAY OF ZEOLITES Amount of Amount of 2.2M 2.2 M Solution Amount of Solution Amounts of of 8.88 M of 11.1 M Na₂O· Solution Na₂O · Solution Reaction Al₂O₃ · of 2SiO₂ · of Amount ofRegion 5H₂O (μL) KOH (μL) 5H₂O (μL) NaOH (μL) H₂O (μL) 1 100 0 100 80480 2 100 0 100 80 1280 3 100 0 200 40 420 4 100 0 200 40 1220 5 100 0100 320 240 6 100 0 100 320 1040 7 100 0 200 280 180 8 100 0 200 280 9809 100 200 100 80 280 10 100 200 100 80 1080 11 100 200 200 40 220 12 100200 200 40 1020 13 100 200 100 320 40 14 100 200 100 320 840 15 100 200200 280 0 16 100 200 200 280 800

[0177] D. Synthesis of an Array of Copper Oxide Compounds Using SprayingDeposition Techniques

[0178] This example illustrates the synthesis of an array of differentcopper oxide compounds using spraying deposition techniques. Thereactants are delivered to a 1.25 cm×1.25 cm MgO substrate having 16predefined regions thereon. The reactants are delivered in the form ofthin-films using a sprayer in combination with physical maskingtechniques. The sprayer used in this example is a Sinitek 8700-120MSultrasonic sprayer. At a water flow rate of 0.26 GPM and a frequency of120 KHz, this sprayer can generate a cone-line spraying pattern of 2inches and a droplet diameter of 18 microns.

[0179] The four components used in this example to generate the array ofinorganic materials are Bi(NO)₃, Cu(NO₃)₃, Ca(NO₃)₃ and Si(NO₃)₃. Thesecomponents were dissolved in water to concentrations of 0.8 M, 2 M, 2 Mand 2 M, respectively. The pH of the Bi(NO₃)₃ solution was about 0.9. Indelivering the reactants to the predefined regions on the substrate, itis important to control the flow rate of the sprayer as well as thetemperature of the substrate so that the reactant droplets dryimmediately upon contact with the substrate surface. The flow rate usedwas kept at about 0.26 GPM, and the temperature of the substrate wasmaintained at about 2100 C. In addition, it is important to control thespraying time so that the amount, i.e., moles, of each reactant isapproximately the same. The spraying time was such that each of thethin-layer films deposited on the surface of the substrate had athickness of about 1 to 4 microns.

[0180] Using a binary masking strategy, the aqueous solutions ofCa(NO₃)₃, Bi(NO₃)₃, Cu(NO₃)₃ and Si(NO₃)₃ were delivered, in this order,to the substrate using the following steps. As mentioned, the MgOsubstrate had 16 predefined regions 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15 and 16. In a first masking step, regions 9, 10, 11, 12,13, 14, 15, and 16 were masked and an aqueous solution of Ca(NO₃)₃ wasdelivered to the exposed regions in the form of a thin-film. Thereafter,in a second masking step, the mask was repositioned so that regions 3,4, 7, 8, 11, 12, 15 and 16 were masked, and an aqueous solution ofBi(NO₃)₃ was delivered to the exposed regions in the form of athin-film. In a third masking step, regions 5, 6, 7, 8, 13, 14, 15 and16 were masked, and an aqueous solution of Cu(NO₃)₃ was delivered to theexposed regions in the form of a thin-film. Finally, in a fourth maskingstep, regions 2, 4, 6, 8, 10, 12, 14 and 16 were masked, and an aqueoussolution of Si(NO₃)₃ was delivered to the exposed regions in the form ofa thin-film.

[0181] Once the components of interest were delivered to the appropriatepredefined regions on the substrate, the substrate having the array ofreactants thereon was oxidized at 300° C. to remove any nitrogen fromthe array. Thereafter, the substrate was flash heated at 880° C. forabout 2 minutes and rapidly quenched on a copper block. Thereafter, thearray of materials was screened for superconducting material.

[0182] E. Synthesis of an Array of Manganese Oxide Thin-film Materials

[0183] This example illustrates the possible synthesis and screening ofan array of manganese oxide thin-film materials. The reactants aredelivered to a 1.25 cm×1.25 cm LaAlO₃ substrate with a (100) polishedsurface. The substrate having 16 predefined regions thereon is containedin a reaction chamber in vacuo. The reactants are delivered to thesubstrate in the form of thin-films using a sputtering system incombination with binary masking techniques. The binary mask is made ofstainless steel. A RF magnetron gun sputtering system is used to deliverthe reactant components to the predefined regions on the substrate. TheRF magnetron sputtering gun (Mini-mak manufactured by US, Inc.,Campbell, Calif.) used is about 1.3 inches in diameter. With RF inputpower (supplied by a Plasmtherm-2000 with a matching network) of 50 toabout 200 W, deposition rates ranged from about 0.3 Å/s to about 2 Å/sfor the five different reactant components. The RF magnetron sprayer ispositioned about 3 to 4 inches above the substrate and the uniformity ofdeposited film is about 5% over a 1 to 2 inch diameter area. Thesputtering gas flow (Ar or Ar and O₂) is controlled by metering valvesand differential pumping through a manual gate valve. To achieve a highdeposition rate, it is determined that the best pressure range is about5 to 15 mTorr. The partial pressure of each gas component in the chamberis monitored using a residual gas analyzer (Micropole Sensor by FerranScientific, San Diego, Calif.) directly up to 15 mTorr withoutdifferential pumping.

[0184] The reactant components used to generate the array of copperoxide materials are as follows: MnO₂, La₂O₃, CaO, SrF₂, and BaF₂. MnO₂is used as the base element in an effort to discover new manganese oxidematerials and, thus, this component is delivered to each of the 16predefined regions on the substrate. Prior to delivering the componentof interest to the predefined regions on the substrate, the base airpressure of the reaction chamber is lowered, within 10 to 15 minutes, toabout 10⁻⁵ to 10⁻⁴ Torr by a 250 l/s turbo pump and, thereafter, it isfurthered lowered to 10⁻⁸ Torr using extended pumping time incombination with heating the reaction chamber to about 100° C. to about150° C. Since only a single RF magnetron gun sputtering system isemployed, the vacuum is broken and reestablished each time the componentis changed. The film deposition thickness is monitored using a crystalmicro-balance (STM-100 by Sycon Instruments, Syracuse, N.Y.).

[0185] The reactant components are delivered to the LaAlO₃ substrate inthe following order: MnO₂, La₂O₃ CaO, SrF₂, and BaF₂. The stoichiometryis designed so that each of the five components is present in equalmolar amounts, i.e., 2 M:1 La:1 Ca:1 Sr:1 Ba as deposited film. Thetotal thickness of the film is about 0.4 μm for a five layered site. Thethickness of each of the individual films as well as the sputteringrates at which each of the components are deposited are set forth inTable V, supra. TABLE V DEPOSITION THICKNESS AND SPUTTERING RATE FOR THECOMPONENTS USED TO GENERATE AN ARRAY OF MANGANESE OXIDES ComponentDeposition Thickness Sputtering Rate La₂O₃ 480 Å 0.3 Å/SEC MnO₂ 1000 Å   1 Å/SEC BaF₂ 1040 Å  0.3 Å/SEC SrF₂ 860 Å 0.3 Å/SEC CaO 480 Å 0.3Å/SEC

[0186] Once the components of interest are delivered to the 16predefined regions on the substrate, the substrate is placed in afurnace, and the components are subsequently reacted. The components aresimultaneously reacted using the following heating and coolingprocedure: 50° C. to 840° C. in 2 hr., 840° C. to 900° C. in 0.5 hr. and900° C. to 840° C. in 0.5 hr. Once the substrate cools to a temperatureof about 840° C., the power is turned off. The heating and coolingprocedure is performed in ambient atmosphere. No apparent evaporation ormelting is observed.

[0187] Once reacted, each of the 16 predefined reaction regions arescreened for giant magnetoresistant (GMR) materials using a 12 Telsasuperconducting magnet cryostat (manufactured by Janis Research Co.,Inc., Willmington, Mass.) using contact measurement techniques.Non-contact measurement techniques using similar scanning detectionsystems for high T_(e) materials can also be applied to increase theefficiency and resolution.

[0188] F. Synthesis of an Array of 16 Different Zinc Silicate Phosphors

[0189] This example illustrates the possible synthesis of an array of 16different zinc silicate phosphors. A 1 mm×1 mm pyrex substrate having 16predefined regions thereon is used in this example. Each of thepredefined regions is 100 μm×100 μm×500 μm and, thus, the volume of eachpredefined region is about 5,000 picoliters. To ensure the reactants ina given region do not move to adjacent regions, 3,000 picoliter reactionvolumes will be used.

[0190] The reactants will be delivered simultaneously to each region onthe substrate using an ink-jet dispenser having three nozzles. The firstnozzle is connected to a reservoir containing a 1M solution of ZnO inwater. To generate an array of 16 different phosphors, the reactantamounts set forth in Table VI, infra, are delivered to the 16 predefinedregions on the substrate. The synthesis reaction is carried out under anitrogen atmosphere for a period of 2 hrs. at 1400° C. Once formed, eachof the 16 predefined reaction regions is screened for electroluminescentmaterials or phosphors by radiating the sample with a specificexcitation wavelength and recording the emission spectra with aPerkin-Elmer LS50 spectrofluorimeter. TABLE VI VARIOUS REACTANTCOMPONENTS USED TO GENERATE AN ARRAY OF ZINC SILICATE PHOSPHORS MnCO₃Reaction Region SiCO₂ (picoliters) ZnO 1 1500 1425   75 2 1500 1350  1503 1500 1275  225 4 1500 1200  300 5 1500 1125  375 6 1500 1050  450 71500 975 525 8 1500 900 600 9 2000 950  50 10  2000 900 100 11  2000 850150 12  2000 800 200 13  2000 750 250 14  2000 700 300 15  2000 650 35016  2000 600 400

X. CONCLUSION

[0191] The present invention provides greatly improved methods andapparatus for the parallel deposition, synthesis and screening of anarray of materials on a single substrate. It is to be understood thatthe above description is intended to be illustrative and notrestrictive. Many embodiments and variations of the invention willbecome apparent to those of skill in the art upon review of thisdisclosure. Merely by way of example a wide variety of process times,reaction temperatures and other reaction conditions may be utilized, aswell as a different ordering of certain processing steps. The scope ofthe invention should, therefore, be determined not with reference to theabove description, but instead should be determined with reference tothe appended claims along with the full scope of equivalents to whichsuch claims are entitled.

What is claim is:
 1. A method of making an array of materials, saidmethod comprising: (a) delivering a first component of a first materialand a first component of a second material to first and second regionson a substrate; (b) delivering a second component of said first materialand a second component of said second material to said first and secondregions on said substrate; and (c) simultaneously reacting saidcomponents to form at least two materials.
 2. The method as recited inclaim 1 wherein said materials are covalent network solids.
 3. Themethod as recited in claim 1 wherein said materials are ionic solids. 4.The method as recited in claim 1 wherein said materials are molecularsolids.
 5. The method as recited in claim 1 wherein said materials areinorganic materials.
 6. The method as recited in claim 5 wherein saidinorganic materials are intermetallic materials.
 7. The method asrecited in claim 5 wherein said inorganic materials are metal alloys. 8.The method as recited in claim 5 wherein said inorganic materials areceramic materials.
 9. The method as recited in claim 1 wherein saidmaterials are organometallic materials.
 10. The method as recited inclaim 1 wherein said materials are composite materials.
 11. The methodas recited in claim 1 wherein said materials are non-biological organicpolymers.
 12. The method as recited in claim 1 wherein said firstcomponent of said first material and said second component of said firstmaterial are simultaneously delivered to said first region.
 13. Themethod as recited in claim 1 wherein said first component of said firstmaterial and said first component of said second material aresimultaneously delivered to said first region and said second region,respectively.
 14. The method as recited in claim 1 wherein said firstcomponent of said first material and said first component of said secondmaterial are the same, but are offered in different concentrations. 15.The method as recited in claim 1 wherein said second component of saidfirst material and said second component of said second material are thesame, but are offered in different concentrations.
 16. The method asrecited in claim 1 wherein said first component of said first materialis delivered to said first region in a gradient of stoichiometries. 17.The method as recited in claim 1 wherein said first component of saidfirst material and said first component of said second material are thesame, but are offered to said first and second regions on said substratein a gradient of stoichiometries.
 18. The method as recited in claim 1wherein the components of said materials are delivered to said first andsecond regions on said substrate from a pipette.
 19. The method asrecited in claim 1 wherein the components of said materials aredelivered to said first and second regions on said substrate from apulse pressure ink-jet dispenser.
 20. The method as recited in claim 1wherein the components of said materials are delivered to said first andsecond regions on said substrate from bubble jet ink-jet dispenser. 21.The method as recited in claim 1 wherein the components of saidmaterials are delivered to said first and second regions on saidsubstrate from a slit jet ink-jet dispenser.
 22. The method as recitedin claim 1 wherein said steps of delivering said components eachcomprises the following steps: (i) identifying a reference point on saidsubstrate; (ii) moving a dispenser of said component a fixed distanceand direction from said reference point such that said dispenser ispositioned approximately above said first region on said substrate;(iii) delivering said component to said first region; and (iv) repeatingsteps (ii) and (iii) for each remaining component for each remainingregion.
 23. The method as recited in claim 1 wherein said step ofdelivering said first component of said first material to said firstregion on said substrate comprises the steps of: (i) placing a maskadjacent to said substrate, said mask permitting said first component ofsaid first material to be delivered to said first region on saidsubstrate, but not to said second region on said substrate; (ii)delivering said first component of said first material to said firstregion on said substrate; and (iii) removing said mask.
 24. The methodas recited in claim 1 wherein said step of delivering said firstcomponent of said first material to said first region on said substratecomprises the steps of: (i) placing a mask adjacent to said substrate,said mask permitting said first component of said first material to bedelivered to said first region on said substrate, but not to said secondregion on said substrate; (ii) depositing a thin-film of said firstcomponent of said first material on said first region on said substrate;and (iii) removing said mask.
 25. The method as recited in claim 1wherein said step of delivering said first component of said firstmaterial to said first region on said substrate comprises the steps of:(i) placing a mask adjacent to said substrate, said mask permitting saidfirst component of said first material to be delivered to said firstregion on said substrate, but not to said second region on saidsubstrate; (ii) spraying said first component of said first materialonto said first region on said substrate; and (iii) removing said mask.26. The method as recited in claim 1 wherein said step of deliveringsaid first component of said first material to said first region on saidsubstrate comprises the steps of: (i) depositing a photoresist on saidsubstrate; (ii) selectively exposing said photoresist on said substrate;(iii) selectively removing said photoresist from said substrate toexpose said first region; (iv) delivering said first component of saidfirst material to said first region on said substrate; and (v) removingremaining photoresist from said substrate.
 27. The method as recited inclaim 1 wherein said step of delivering said first component of saidfirst material to said first region on said substrate comprises thesteps of: (i) delivering said first component of said first material tofirst and second regions on said substrate; (ii) depositing aphotoresist on said substrate; (iii) selectively exposing saidphotoresist on said substrate; (iv) selectively removing saidphotoresist from said second region on said substrate, thereby exposingsaid first component of said first material; (v) etching off the exposedfirst component of said first material; and (vi) removing remainingphotoresist from said substrate.
 28. The method as recited in claim 1wherein each of said materials is synthesized in an area of less than 25cm².
 29. The method as recited in claim 1 wherein each of said materialsis synthesized in an area of less than 10 cm².
 30. The method as recitedin claim 1 wherein each of said materials is synthesized in an area ofless than 5 cm².
 31. The method as recited in claim 1 wherein each ofsaid materials is synthesized in an area of less than 1 cm².
 32. Themethod as recited in claim 1 wherein each of said materials issynthesized in an area of less than 1 mm².
 33. The method as recited inclaim 1 wherein each of said materials is synthesized in an area of lessthan 10,000 μm².
 34. The method as recited in claim 1 wherein each ofsaid materials is synthesized in an area of less than 1,000 μm².
 35. Themethod as recited in claim 1 wherein each of said materials issynthesized in an area of less than 100 μm².
 36. The method as recitedin claim 1 wherein each of said materials is synthesized in an area ofless than 1 μm².
 37. The method as recited in claim 1 wherein at least10 different materials are synthesized on said substrate.
 38. The methodas recited in claim 1 wherein at least 100 different materials aresynthesized on said substrate.
 39. The method as recited in claim 1wherein at least 100 different materials are synthesized on saidsubstrate.
 40. The method as recited in claim 1 wherein at least 10⁶different materials are synthesized on said substrate.
 41. The method asrecited in claim 1 wherein at least 100 different materials aresynthesized, and each different material is contained within an area ofabout 1 mm² or less.
 42. The method as recited in claim 1 furthercomprising the step of screening said array of materials for a usefulproperty.
 43. The method as recited in claim 42 wherein said usefulproperty is an electrical property.
 44. The method as recited in claim42 wherein said useful property is a thermal property.
 45. The method asrecited in claim 42 wherein said useful property is a mechanicalproperty.
 46. The method as recited in claim 42 wherein said usefulproperty is a morphological property.
 47. The method as recited in claim42 wherein said useful property is an optical property.
 48. The methodas recited in claim 42 wherein said useful property is a magneticproperty.
 49. The method as recited in claim 42 wherein said usefulproperty is a chemical property.
 50. The method as recited in claim 42wherein said array of materials is screened in parallel.
 51. The methodas recited in claim 42 wherein said array of materials is screenedsequentially.
 52. An array of more than 10 different inorganic materialson a substrate at known locations thereon.
 53. The array as recited inclaim 52 wherein more than 100 different inorganic materials on asubstrate at known locations thereon.
 54. The array as recited in claim52 wherein more than 10³ different inorganic materials on a substrate atknown locations thereon.
 55. The array as recited in claim 52 whereinmore than 10⁶ different inorganic materials on a substrate at knownlocations thereon.
 56. The array as recited in claim 52 wherein saidinorganic materials are intermetallic materials.
 57. The array asrecited in claim 52 wherein said inorganic materials are metal alloys.58. The array as recited in claim 52 wherein said inorganic materialsare ceramic materials.
 59. The array as recited in claim 52 wherein saidinorganic materials are inorganic-organic composite materials.
 60. Amethod of making at least two different arrays of materials, said methodcomprising: (a) delivering a first component of a first material to afirst region on a first substrate and delivering said first component ofsaid first material to a first region on a second substrate; (b)delivering a first component of a second material to a second region onsaid first substrate and delivering said first component of said secondmaterial to a second region on said second substrate; (c) delivering asecond component of said first material to said first region on saidfirst substrate and delivering said second component of said firstmaterial to said first region on said second substrate; (d) delivering asecond component of said second material to said second region on saidfirst substrate and delivering said second component of said secondmaterial to said second region on said second substrate; and (e)reacting said components on said first substrate under a first set ofreaction conditions and said components on said second substrate under asecond set of reaction conditions to form at least two different arraysof at least two materials.
 61. The method as recited in claim 60 whereinsaid materials are covalent network solids.
 62. The method as recited inclaim 60 wherein said materials are ionic solids
 63. The method asrecited in claim 60 wherein said materials are molecular solids.
 64. Themethod as recited in claim 60 wherein said materials are inorganicmaterials.
 65. The method as recited in claim 64 wherein said materialsare intermetallic materials.
 66. The method as recited in claim 64wherein said inorganic materials are metal alloys.
 67. The method asrecited in claim 64 wherein said inorganic materials are ceramicmaterials.
 68. The method as recited in claim 60 wherein said materialsare organometallic materials.
 69. The method as recited in claim 60wherein said materials are composite materials.
 70. The method asrecited in claim 60 wherein said materials are non-biological organicpolymers.
 71. The method as recited in claim 60 wherein said first setof reaction conditions differs from said second set of reactionconditions in terms of the temperature at which the reactions arecarried out.
 72. The method as recited in claim 60 wherein said firstset of reaction conditions differs from said second set of reactionconditions in terms of the pressure at which the reactions are carriedout.
 73. The method as recited in claim 60 wherein said first set ofreaction conditions differs from said second set of reaction conditionsin terms of the reaction times at which the reactions are carried out.74. The method as recited in claim 60 wherein said first set of reactionconditions differs from said second set of reaction conditions in termsof the atmosphere in which the reactions are carried out.
 75. The methodas recited in claim 60 wherein said first component of said firstmaterial and said first component of said second material are the same,but are offered in different concentrations.
 76. A material having auseful property prepared by a process comprising the steps of: (a)forming an array of different materials on a single substrate; (b)screening said array for a material having said useful property; and (c)making additional amounts of said material having said useful property.77. The material as recited in claim 76 wherein step (a) of said processfurther comprises the steps of: (i) delivering a first component of afirst material and a first component of a second material to first andsecond regions on a substrate; (ii) delivering a second component ofsaid first material and a second component of said second material tofirst and second regions on said substrate; and (iii) simultaneouslyreacting said components to form said array of at least two differentmaterials.
 78. The material as recited in claim 77 wherein said firstcomponent of said first material and said first component of said secondmaterial are the same, but are offered in different concentrations. 79.The material as recited in claim 76 wherein said material is a covalentnetwork solid.
 80. The material as recited in claim 76 wherein saidmaterial is an ionic solids.
 81. The material as recited in claim 76wherein said material is a molecular solid.
 82. The material as recitedin claim 76 wherein said material is an inorganic material.
 83. Themethod as recited in claim 82 wherein said inorganic material is anintermetallic material.
 84. The method as recited in claim 82 whereinsaid inorganic material is a metal alloy.
 85. The method as recited inclaim 82 wherein said inorganic material is a ceramic material.
 86. Themethod as recited in claim 76 wherein said material is an organometallicmaterial.
 87. The method as recited in claim 76 wherein said material isa composite material.
 88. The method as recited in claim 76 wherein saidmaterial is a non-biological organic polymer.
 89. The method as recitedin claim 76 wherein said material is a high temperature superconductor.90. The method as recited in claim 76 wherein said material is amagnetoresistive material.
 91. The method as recited in claim 76 whereinsaid material is a zeolite.
 92. The method as recited in claim 76wherein said material is a phosphor.
 93. The method as recited in claim76 wherein said material is a conducting polymer.